Morphology of Flustra membranaceo-truncata.-W. J. Vigelius makes this essay an introduction to a proposed work on the morphology of the marine Bryozoa. The species of Flustra which he has examined offers another proof of the truth of the doctrine that the mode of growth of the Bryozoan stock is of no value as a means of distinguishing the families. The nutrient animal and the avicularium are alone distinctly differentiated individuals; the brood-capsules are only organs, not individuals. The nutrient animals may be (1) budding: these are found on the marginal zone of the colony; (2) perfect: these are the reproductive forms; (3) resting; and (4) decaying. The two last are only found near the proximal part of the stock, and are much rarer than the others. The cystid and polypid make up the complete nutrient animal, and in the normal condition consist of integument, nutrient apparatus, and parenchymatous tissue. The author has not been able to convince himself of the existence of a nervous system, but he thinks that its centre is perhaps represented by the small rounded mass of cells, which lies on the anal side of the anterior wall of the pharynx. Like other writers at the present time, the author has made some observations on spermatogenesis, and finds that the spermatoblasts are derived from the repeated division of the spermatospores, but they do not form rounded or oval masses of regularly arranged cells placed on a nutrient blastophore. Vigelius is uncertain whether the explanation of the absence of the blastophore is to be found in the occurrence here of a more primitive condition of things, or in the fact that the surrounding perigastric fluid is bighly nutritious. When the spermatoblasts become converted into spermatozoa they are at first pyriform; the tail then arises at the narrow end, and becomes of some length.

The histolysis of the digestive tract is described, and the brown body is regarded as having certainly a nutrient function. The view that the cystid and polypid are parts of one and the same individual is supported by the observations of Barrois, the organization of the complete nutrient animal, and the history of the process of germination. The objection that the living cystid appears separately is of little weight, now that Vigelius has shown that the modifications of the cystid are not so numerous as Nitsche supposed-for example, the primitive avicularia are not cystids but polypocystids, the rootfilaments are organs, and not individuals, and the same is true of the brood-capsules. As to the objections based on the periodical disappearance and subsequent regeneration of the enteric canal, an answer is to be found in the general dictum that morphological facts must not be looked at from a physiological standpoint, as well as in the fact of the wide distribution of the phenomena of regeneration among lower animals.

The perigastric space is regarded as being a true cœlom, but at the same time Vigelius adopts the view of the Brothers Hertwig, that the Polyzoa are pseudo-cœlia.

* Biol. Centralbl., iii. (1884) pp. 705–21.

Arthropoda.

a. Insecta.

Coræbus bifasciatus.*-A. Laboulbène discusses the sexual differences of this Coleopteron, and the characters of its so-called eggs. He finds that the male has been mistaken for the female, and that the oviform bodies are true Acari, in the body of which developing ova were to be detected; the oviform body, then, is nothing but the globular abdomen of the mite, which is swollen out into a vesicle more like that of Termites or Pulex penetrans than anything which is found in any other acarid of the same family.

Mouth Parts of Diptera.t-The descriptive part of H. J. Hansen's work is preceded by a full historical account of the work of others, from Swammerdam to the recent writers, such as Dimmock, Becher, Meinert and Kräpelin. It is written in Danish, with a Latin abstract, or "Conspectus systematicus," of the chief results, and the explanations of the plates are both in Danish and Latin.

Mouth-Organs of Lepidoptera.-P. Kirbach, after an account of what is generally known as to the structure of the mouth-organs of insects in general, and of Lepidoptera in particular, proceeds to his own observations. With regard to the histological structure of the proboscis, he points out that the lowest portion is distinctly lamellar, and consists of thin transparent layers, while the upper portion has chitinous bodies deposited in its otherwise homogeneous ground substance; these bodies are set at pretty regular distances, and always have their broadest surface turned outwards. True scales, completely analogous to those of the wings and other parts of the body, are to be found on the maxillæ of many moths and of some butterflies.

The author has been interested in the formation of the rod-like bodies found within the closed sucking canal; he was at first inclined to ascribe to them a gustatory function, but this was opposed by their possession of a chitinous membrane, and by the presence of true gustatory organs within the mouth. Nor can they have an olfactory function, but must rather be tactile organs which test the fluidity and viscidity of the fluid-a not unimportant function, as the quantity of saliva that has to be mixed with the food depends on the degree of its viscidity.

In answer to the very interesting question as to how the sucking canal is formed, the author points out that, owing to the close apposition of the two maxillæ, a tube is formed through the whole length of the proboscis, and this is nearly circular. How are the maxillæ kept closely united and the canal so closed as to be air-tight without restraining the powers of movement of the proboscis? A series of closely-applied, thin, chitinous plates are inserted into the chitinous ridges which are placed near the sides of the groove; these plates are

*Comptes Rendus, xcviii. (1884) pp. 539-41.

+ H. J. Hansen, Fabrica Oris Dipterorum,' part 1 (Tabanidæ, Bombyliidæ, Asilidæ, Thereva, Midas, Apiocera), 8vo, Copenhagen, 1883, 250 pp. and 5 pls. See Amer. Natural., xviii. (1884) p. 274.

Arch. f. Naturg., 1. (1884) pp. 78-119 (2 pls.).

set horizontally and are much longer than broad; they are so arranged that the clefts between the separate plates are covered over as completely as possible; in Vanessa, the marginal plates are beset with lateral teeth. In Pieris, the last eighth of the proboscis has its plates smaller, and their course is oblique and upwards, instead of horizontal; the spaces between the plates are larger, but a compensation is afforded by the development of spines. The differences which obtain in various Lepidoptera are noted, but in all it is clear that a maximum of strength obtains with a maximum power of movement.

The mechanism of sucking may be thus described :-When a butterfly thinks it has lit upon suitable food it tests it with the tactile corpuscles of the protruded proboscis, and then slips the top of the proboscis into the fluid; with this it mixes a certain quantity of saliva. The frontal, lateral, and dorsal muscles contract, and so draw up the operculum of the pharynx; by this means a large cavity is formed. At the same time the elevator muscle of the oral valve contracts, and the oral and proboscidial canal are put into communication with the pharynx, which is almost empty of air. The pressure of the atmosphere drives the fluid into the canal of the proboscis. As the opercular muscles relax, the longitudinal and transverse muscles contract, and by this means the fluid is forced into the oesophagus. When the latter muscles relax, the opercular muscles come together, the œsophageal valve closes the hinder opening, the oral valve rises, and a second stream of fluid enters the pharynx. These acts follow one another so quickly and so regularly that a continuous stream enters the canal of the proboscis. It will be seen that the author's account differs from that of preceding writers, and he is, apparently, justified in contending that it is the only one which falls in with the anatomical facts.

Malpighian Vessels of Lepidoptera.*-M. Cholodkovsky has lately added Tineola biselliella to the list of the few insects that are known to have only two Malpighian vessels; these are of some size, and are folded along the course of the digestive canal, and end by a distinct enlargement. Suckow has described four Malpighian vessels in a species of Pterophorus, and of Hyponomenta, but later investigations show that they really agree with the great majority of the Lepidoptera in having six. As embryological research has shown that a small number of Malpighian tubules is a primitive character, and that with progressive development the number increases either by branching or by histolysis, succeeded by a fresh development of a larger number, it is clear that the Microlepidoptera in which there are but two, while their caterpillars have six, exhibit just the reverse to what we should expect-or, in other words, we have here a case of atavism, and one which, as it obtains in the imaginal state only, is a periodic rather

than a constant atavism.

Abdominal Muscles of the Bee.t-G. Carlet distinguishes three regions in the abdominal musculature of the bee-dorsal, lateral, and *Comptes Rendus, xcviii. (1884) pp. 631-3. + Ibid. (1883) pp. 758-9.

ventral. All of them, with the exception of the alæ cordis, which subserve the function of circulation -and they are more numerous than is generally supposed-take part in respiration, and consequently in the production of heat, which is so important a function in the economy of the bee. The mechanism is more complicated than is ordinarily believed, for when the abdomen shortens or elongates the dorsal and ventral surfaces approach or separate from one another; in other words, the abdomen dilates or contracts along three axes to admit or expel air by its stigmata.

Flight of Insects.*-Dr. Amans has a second essay† on the flight of insects, in which he describes the organs of the Orthoptera.

Aphides of the Elm.-J. Lichtenstein records some observations which have enabled him to establish the fact of the migration of the Aphides of the elm (Tetraneura ulmi) to the roots of grasses, and their return to the trunks of the trees in autumn.

8. Myriopoda.

Head of Scolopendra.§-This memoir (in English) treats in detail of the external anatomy of the parts of the head in Scolopendra subspinipes Kohlr., as most typical of the Chilopods. The details appear to have been worked out with care, while the drawings seem to have been very carefully made by the author, and beautifully engraved.

In the course of his lengthy review of the works of his predecessors, the author criticizes and disproves Newport's views that the head of the Chilopods is composed of eight subsegments. Four pages of the memoir are devoted to an elaborate and useful tabular view of the opinions of forty-six authors as to the morphology and nomenclature of the mouth-parts. Dr. Meinert gives a new explanation and nomenclature of the mouth-parts. He also claims that they are analogous with those of biting insects, or, to use his own words, "it is purposed to serve me to show the coincidence of the head of Chilopoda and its parts of the mouth with the head of the Insect and its parts of the mouth, especially in the Orthoptera, that is to say, in insects with free biting parts of the mouth, and four pairs of these parts or four metamers in the head." He does not regard the antennæ and the antennal segment as homologues of the other mouth-parts and segments. In his own words, "The real head then must be said to consist of the three foremost metamers, together with their exponents or limbs; that is to say, the labium, the maxillæ and the mandibles, and besides of the lamina cephalica, which latter, as well as its appendages, the antennæ, I by no means can consider to be homonomeous with the other metamers of the body and of the head, and with their exponents."

*Rev. Sci. Nat., iii. (1883) pp. 121-39 (2 pls.).

+ See this Journal, iii. (1883) p. 832.

Comptes Rendus, xcvii. (1883) p. 1572.

SF. Meinert, Caput Scolopendra. The Head of the Scolopendra and its Muscular System,' 77 pp. and S pls. 4to, Copenhagen, 1883. See Amer. Natural., xviii. (1884) pp. 270–2.

7. Arachnida.

Skeletotrophic Tissues and Coxal Glands of Limulus, Scorpio, and Mygale.-E. Ray Lankester points out the necessity for a detailed and comprehensive study of the connective and other tissues of the skeletotrophic group in both Arthropoda and Mollusca "before we can pretend to offer any satisfactory account of the vascular system in those groups, and of the 'lacunar' connection between arteries and veins, which is confidently described and discussed by all zoologists, but has never yet been demonstrated to exist in a manner satisfying the requirements of modern histology."

In the account of the structure of the entosternites, the author says that it seems possible to morphologically define "cartilage" by the isolation of each one of its constituent cells in a firm matrix, and by the triaxial multiplication of those cells, whether the matrix be homogeneous, fibrillated, or penetrated by reticular condensations. A well-marked entosternite has for the first time been found among the Crustacea, and, curiously enough, in the most archaic form, Apus. After a careful description of the various forms of connective tissue the author passes to the blood-corpuscles of Limulus and Scorpio, which agree remarkably in form, size, and granulation; both contain a large quantity of hemocyanin, and are both, in bulk, of a deep indigo-blue colour.

The coxal glands are next dealt with; their minute structure points to their forming an active secretory apparatus, the materials for which are brought to them by the intercæcal tissue; they may well be compared with the green glands (antennary coxal glands) of the Decapod Crustacea, from which, however, they differ in having no definite outlet, and in the structure of the epithelial cells. The author justly points to the occurrence of "these glands in their characteristic position, and with their characteristic corticated secretory cells in Limulus on the one hand, and in Scorpio and Mygale on the other," as another argument in favour of that classificatory alliance of Limulus with the Arachnida, of which he has, in earlier essays, afforded so many instructive demonstrations.

8. Crustacea.

Liver of Decapods.†-J. Frenzel gives a short account of the results of his investigation of the gland of the mid-gut, or liver, of twenty-six species of Decapods. The epithelium of this gland consists of fat-cells and ferment-cells; the size of them does not seem to differ with that of the individual, but to be pretty constant in each species. In Carcinus they are 07 mm. and in Palinurus ⚫06 mm. in diameter. In section, each tube of the gland is seen to be invested by a delicate fringe, which is more or less distinctly striated, and which has the function of a porous cuticle. The longitudinal striation seen in the upper part of the cells calls to mind that which obtains in the cells of the mid-gut of insects and * Quart. Journ. Micr. Sci., xxiv. (1884) pp. 129–62 (7 pls.). † SB. K. Akad. Wiss. Berlin, xlii. (1883) pp. 1113–9.