are better developed than in Muranoides, their position is more anterior, and a spine and two rays of moderate size exist. (Proc. U. S. Nat. Mus. v. 8, pp. 192, 192.)

The American Flying Fishes.-The fishes of the sub-family of Exocœtines, including the true flying fishes, have been examined recently by Messrs. Jordon and Meek, and it appears that seventeen species referable to four genera are recognizable as inhabitants of the American waters on both sides of the continent. Three of these, Fodiator acutus, Parexocatus mesogaster, and Halocypselus evolans, belong to special genera, while all of the others are members of one natural genus (Exocœtus). Eight of the Exocetines have been obtained off the Atlantic coast of the United States and one (Exocatus Californicus) along the Pacific coast. The California flying fish is one of the largest of the family. (Proc. U. S. Nat. Mus., v, 8, pp. 67.)

Amphibians.

The Retrograde Metamorphosis of Siren.-The remarkable eel-like amphibian named Siren lacertina, and abundant in the southern parts of the United States, is the type of a group, by some considered as an order, distinguished by some remarkable characteristics; some of these have been considered to be evidences of degeneration. Professor Cope has now reason to believe that there are also indications to be found of "a retrograde metamorphosis" in the "history of its branchial apparatus." He had been at a loss to account for the curious condition frequently observed in the branchiæ of the sirens. The fringes are frequently partially atrophied and "inclosed in a common dermal investment of the branchial ramus, or all the rami are covered by a common investment, so as to be completely functionless and immovable. This character, observed in the Pseudobranchus striatus, gave origin to its separation from the genus Siren." The character is however also observable in the typical species, Siren lacertina, at a certain age, and the real difference, so far as generic valuation is concerned, depends simply on the different number of the digits represented in the two species.

Professor Cope surprised "on discovering that the functionless condition of the branchiæ is universal in young individuals of Siren lacertina of 5 and 6 inches in length;" and even in a specimen little more 3 inches long they were found "entirely rudimentary and sub-epidermal;" in fact, according to Professor Cope, only in large adult specimens are the branchiæ fully developed. The inference drawn from the facts is, that "the branchiæ are in the Sirens not a larval character, as in other perennibrachiate Batrachia, but a character of maturity. Of course, only direct observation can show whether Sirens have branchiæ on exclusion from the egg; but it is not probable that they differ so much from the

other members of their class as to be without them. Nevertheless, it is evident that the branchiæ soon become functionless, so that the animal is almost, if not exclusively, an air breather, and that functional activity is not resumed till a more advanced age." Indeed, from observations of a specimen in an aquarium, which for a time had no branchiæ at all, it appeared that "sirens may be exclusively air breathers." Professor Cope urges that in explanation of this fact, it may be remarked that this atrophy cannot be accounted for on the supposition that it is seasonal and due to the drying up of the aquatic habitat of the sirens. The countries they inhabit are humid, receiving the heaviest rainfall of our Eastern States, and there is no dry season. The only explanation appears [to him] to be that the present sirens are descendants of a terrestrial type of batrachia which passed through a metamorphosis like other members of their class, but that more recently they have adopted a permanent aquatic life, and have resumed their branchiæ by reversion." (Am. Nat., v. 20, pp. 1226, 1227.)

Peculiarities of Cæcilians.-The life history of the singular worm-like Amphitrans, representing the order Gymnophiona and the family Cæcibiidæ, is still imperfectly known. Some characteristics have been described recently by the brothers P. B. and C. F. Sarason. In an advanced stage, shortly before hatching, the embryo is provided with very long blood red external gill filaments, and has also a distinct tail, with a strong fin. The gill filaments are shed previous to hatching, after which the young Cæcilians make their way to a neighboring stream, in which they breathe by means of gill slits. After they leave the water their gill slits close up, and they breathe by lungs. There is a fourth gill arch from which the pulmonary artery is given off. The spermatazoon has a spiral filament. The last two facts tend to show that the Cæcilians were nearer to the Modela than to the Anura, as is indeed amply shown to be the case by structural characteristics generally. It seems that there is a difference in reproduction manifested in closely related genera, for some species are oviparous while others are viviparous.

Reptiles.

The classification of the Lizards.-A very important and much needed work has been in progress of publication during the past year in the arrangement and description of the species of living lizards. Two volumes of the projected three of the "Catalogue of Lizards in the British Museum" have already appeared, in which all the species known are described and a number illustrated. The species have been thoroughly revised from a systematic standpoint and grouped into natural genera and families. The classification is mostly based upon such characters as were made use of by Professor Cope about twenty years ago, but which have not received due consideration from later writers. Professor

Cope's work upon the group is indeed the only contribution to the taxonomy of the lizards that is esteemed of special value by the author of the new catalogue. That author is the well-known herpetologist in charge of the reptiles of the British Museum, Mr. George Alfred Boulenger. Mr. Boulenger, however, by no means follows Professor Cope throughout, but has his own well considered views as to the value of the characters first brought prominently forward by Professor Cope. He accepts the order of Lacertians with the limit generally accredited to it of late years. and thus excludes the Sphenontidæ or Hatterüdæ. The order is subdivided into two sub-orders: (1) the Lacertilia vera; (2) the Rhiptoglossa. The several sub-orders into which the former have been disin tegrated by Professor Cope are not recognized and even the families have in some cases been separated, by the intervention of groups adopted by Professor Cope. Twenty-one families of the order are adopted by Mr. Boulenger, and it is interesting to note that three of these were entirely unknown to Duméril and Bibron when, in 1836 to 1839, they pub. lished those volumes of their great work devoted to the order.

The following tabular synopsis of the characters most made use of by Mr. Boulenger will give an idea of the range of variation and systematic values of the various characters. The external form is found to be not only of very little use, in many cases, in the determination of the relations of the types, but sometimes it is very illusive indeed.

The characters utilized for the diagnosis of the various families are almost exclusively derived from the skeleton and teeth, and especially from the consideration of the following elements:

1. The development or non-development of a post-frontal arch (Postfr.). 2. The development or non-development of a post-orbital arch (Postorb.).

3. The development or otherwise of a supra-temporal roof (Suprat. roof).

4. The existence or absence of a columella crani (Col. cr.).

5. The development or non-development of an inter-orbital septum (I. O. s.).

6. The number of parietal bones, i. e., whether paired or single (Par.). 7. The number of frontal bones, whether double or coalesced (Fr.). 8. The number of nasal bones, i. e., whether two or one (Nasals). 9. The number of pre-maxillary bones, i. e., whether one or two pairs (P. max.).

10. The number of elements in each ramus of the lower jaw or mandible, i. e., whether four or five (Mand.).

The teeth, especially whether implanted along the edge of the jaws (acrodent) or on the inner slope (pleurodent) (Teeth).

12. The development of inter-clavicles, i. e., whether "dilated" and "loop shaped proximally," or whether "not dilated proximally” and cruciform (X). Of course in forms whose fore limbs are absent or very much reduced, the inter-clavicles are wanting.

Throwing these characters into diagnostic forms, economy of words and a better idea of the generality of characters may be obtained by recognizing a category called super-family. Under such headings those forms which exhibit exceptional characters may be segregated from the great mass.

The various families recognized by Dr. Boulenger may be found grouped as follows:

Geckonoidea.-Eriglossate saurians with the vertebræ bi-concave, a clavical dilated, and loop-shaped proximally, and post-frontal and postorbital osseus arches undeveloped.

(Geckonida.)-The only Geckonoidea known having the parietal bones

double.

Eublepharoidea.-Eriglossate saurians with concavo-convex vertebræ, clavicle dilated and loop-shaped proximally, and no post-orbital or postfrontal squamosal arches.

(Eublepharida.)-The only known Eublepharoidea simulating in external appearance the Geckonidæ, but distinguished by the coalescence of the parietals into a single bone, as well as by the concavo-convex vertebræ.

Uroplatoidea.-Eriglossate saurians with bi-concave vertebræ, clavicles not dilated proximally, and without post-orbital or post-fronto squamosal bony arches.

(Uroplatida.)-The only known Uroplatoidea having two parietal bones and a minute inter-clavicle.

Pygopodoidea.-Eriglossate saurians with concavo-convex vertebræ,

clavicles dilated and loop-shaped proximally, and no post-orbital or post-fronto squamosal arches.

(Pygopodido.)-The only known Pygopodoidea, especially marked by the exclusion of the frontal from the orbit, by the retention of the pre and post-frontal bones towards each other so that they are in contact.

Agamoidea.-Eriglossate saurians with concavo-convex vertebræ, clavicles not dilated proximally, and without post-orbital or post-frontal squamosal arches.

(Agamidæ.)—Agamoidea with the supra-temporal fossa not roofed over by bone, tongue thickened, and aerodont dentition.

(Iguanidæ.)—Agamoidea with the supra-temporal fossa not roofed over by bone, tongue thickened, and a pleurodont dentition.

(Xenosaurida.)-Agamoidea with the supra-temporal fossa not roofed over by bone, the interior portion of the tongue retractile, a pleurodont dentition, and T-shaped inter-clavicles.

(Zonurida.)-Agamoidea with the supra-temporal fossa roofed over, the tongue simple, and cross-shaped inter-clavicles.

(Anguida.)-Agamoidea with the supra-temporal fossa roofed over; tongue with its anterior portion retractile, with clavicles cross-shaped or absent, and the exo-skeleton developed as osteo-dermal plates, each provided with a system of irregularly arranged aborescent or radiating tubules.

Anielloidea.-Eriglossate saurians, with concavo convex vertebræ, clavicles not dilated posteriorly, and without post-frontal squamosal or post-orbital arches.

(Aniellida.)-The only known anielloidea, distinguished by the absence of ante-orbital septum, and of the columella cranii, and without squamosals.

Helodermatoidea.-Eriglossate saurians with concavo-convex vertebræ; clavicles undilated proximally, and post orbital bony arches, but without post-fronto squamosal arches.

(Helodermatida.)-The only known family of the super-family, distinguished further by the exclusion of the frontal from the orbit on account of the convergence and contact of the pre and post-frontals.

Varanoidea.-Eriglossate saurians, with concavo-convex vertebræ ; clavicles not delated proximally; post-orbital arches, rudimentary or absent, and with post-fronto squamosal arches developed.

(Varanida.)-The only known forms of the type, distinguished further by the union of the nasals into a single bone and the ensheathment of the tongue at its base and its deeply bifid emargination anteriorly.

Lacertoidea.- Eriglossate saurians with the vertebræ concavo-convex; clavicles undilated proximally, and post-fronto squamosal at post-orbital arches developed.

(Xantusiida.)-Lacertoidea with the supra-temporal fossa roofed over and the parietals distinct.