inferior portion of the shaft. They are also separated anteriorly by a shallow open groove. The external condyle is rather more robust than the internal.

The length of the femur is six feet four inches; the elevation

Fig. 16-A caudal vertebra of Amphicalias latus; a from before, b from the left side. of the dorsal vertebra three feet three inches. The animal, if proportioned anteriorly like the Camarasaurus supremus, must have been able to elevate itself to a height of thirty feet. Its length cannot yet be conjectured.

If in this fauna, the Camarasaurus supremus was preeminent in general proportions, and the Amphicælias altus was the tallest, the Amphicalias latus was the most robust. It is represented in Mr. Lucas' collection by a right femur and four caudal vertebræ which are in good preservation. They reveal the existence of another saurian of huge dimensions, and

Fig. 17-Left femur of Amphicalias of great mass in proportion to

its height.

The caudal vertebræ are apparently from the anterior part of the series. They are all strongly biconcave; the anterior face more so than the posterior. They are much more deeply bicon

cave than those of the Camarasaurus supremus; and also differ in their relatively and absolutely greater breadth of body.

The femur is extraordinarily robust. The great trochanter is low, but the shaft is widest where it expands outward. The third trochanter is a ridge, is above the middle, and is short and little prominent. It is on the inner edge of the posterior aspect of the shaft, and looks backwards and inwards. The shaft in its present state is compressed so as to reduce the antero-posterior diameter. It is not however crushed or cracked. The condyles have much greater transverse than antero-posterior extent. They are moderately produced backward, and are separated by a deep popliteal groove, while the anterior trochlear groove is wide and well marked. The inner condyle is narrowed posteriorly, while the external one is obtuse and robust. Their articular faces are marked with irregular pits as in Dystrophæus and Cetiosaurus.

The length of this bone is fifty inches and the thickness fourteen inches. The body of the caudal vertebra is ten inches in transverse diameter.

The character of the articular surfaces of the bones of the limbs already mentioned is a peculiarity of Camarasaurus as well as of the genera named. It indicates a thick cartilaginous cap of the bones, which, if ossified, would be an epiphysis like that of the Mammalia. I first observed this character in the Dystrophæus viæmalæ, a huge saurian discovered by Prof. J. S. Newberry in the red rocks of the Painted Canyon, near the Sierra La Sal, in south-eastern Utah, and described by myself in Lieut Wheeler's final report. The bed from which it was derived is supposed to be of Triassic or Jurassic age. It had an enormous scapula like Camarasaurus, and a long straight humerus; its toes were short. It was probably a predecessor of the gigantic forms from the Dakota formation, and an inhabitant of a more ancient continent. It did not reach the dimensions of either of the species of the genus above-named, or of Amphicælias, having been only as large as an elephant.

The genus Tichosteus included a species not larger than an alligator. Its vertebræ were hollow, but the internal chamber did not communicate with the body cavity. The only known species of Symphyrophus was of similar size, but the vertebral bodies were solid. Some of the numerous crocodile-like teeth found by Mr. Lucas probably belong to species of these genera.

Dr. Hayden visited the locality of Mr. Lucas' excavations, and informs me that the formation from which the Camarasaurus was obtained, is the Dakota. Prof. Marsh has attempted to identify what is, according to Prof. Mudge, the same horizon, one hundred miles north of Canyon City, with the Wealden of England. Specimens from the northern locality which I have examined render it certain that the horizon is that of Mr. Lucas' excavations. Of this I may say that there is no palæontological evidence of its identity with the Wealden. The resemblance of the vertebrate fossils to those of the English Oolite is much greater, but not sufficient as yet for identification.

The discovery of Vertebrata in the strata of the Dakota epoch is an important addition to the geology and palæontology of North America. Credit is due to Superintendent O. W. Lucas for this discovery, and also in an especial manner for the skill and care he has exercised in taking out and shipping the ponderous specimens.

:0:

THE DISCOLORED WATERS OF THE GULF OF CALI

FORNIA.

BY THOS. H. STREETS, M.D., U. S. N.

NE of the earliest names given by the old Spanish navigators to the body of water that lies between the peninsula of Lower California and the western coast of Northern Mexico was the Vermilion sea. It was also known in the earlier times as the Mar de Cortez, and Mar Laurentano; or the Mar Vermiglion, Mar Rojo, and Mar Vermijo, on account of the reddish color of its waters; and more recently as the Mar, or Gulfo, de California.

The names Vermiglion, Vermijo, and Rojo seem to have been applied as early as between the years 1537 and 1540, after the explorations of Ulloa and Alarcon, and from the accounts given of it by Nuño de Guzman and his officers, who were the conquerors and rulers of Sinaloa, a state bordering on the gulf.

In all these narratives, however, it is well to note that two entirely distinct causes of discoloration are confounded. Father Consag and Ugarte, in particular, speak of the brick-colored corrosive water of the gulf-head, which is altogether different from the more vermilion-colored patches at the mouth of the gulf, which were, doubtless, what suggested the name Vermilion sca.

J. Ross Browne, at a recent date, and before him De Mofras, discredited the statements of the old Spanish sailors, and attributed the red color to the reflection in the water of the brilliant, rosy-tinted clouds of sunset.

We had ample opportunity to verify the truth of the Spanish account during the extended survey of the gulf and its shores by the U. S. Steamer "Narragansett," in 1875.

We first saw patches of the red water south of Ciralbo island. The steamer was stopped and a bucket was thrown overboard to secure some of it for examination. The water thus procured revealed nothing when subjected to the test of the microscope; it was perfectly transparent. The failure to discover the cause in this instance was due to the fact that the coloring matter does not float upon the top of the water, but is suspended several feet below; and when this was ascertained, by putting a lead in the bucket and sinking it a half fathom or more below the surface, there was no difficulty in obtaining all that was desired.

When first drawn up and viewed in a glass vessel by the unaided eye the water had a faint reddish tinge. When allowed to stand for a half hour the coloring matter settled to the bottom of the vessel as a greenish-yellow precipitate; and when some of this was taken up by a pipette and examined under the microscope, it was seen to be composed of minute roundish bodies. Further on these were proven to be the remains of ciliate infusoria.

The latter fact was not discovered, however, until after much painstaking investigation. Some small objects had been seen repeatedly to dart across the field of vision when the water was placed fresh upon the glass slide, but they disappeared as they came, like a flash, and it was a long time before their disappearance could be satisfactorily accounted for. The molecules were the only bodies that were permanent, and I was inclined to attribute to them the phenomenon of the water. Finally, one of the little bodies mentioned above stopped directly in the centre of the field of vision, and commenced a rapid rotatory movement, which presently ceased, and the animal was quiescent for a second or two; when lo! a rupture occurred, its molecular contents oozed out, and its transparent envelope became invisible. This then was the solution of the mystery. Afterwards, knowing what to search for, there was no difficulty in seeing the same process repeated again and again.

Mr. Darwin in his "Naturalist's Voyage Around the World," encountered a patch of similarly discolored water off the coast of Peru. According to his account, the water when examined by the microscope was "seen to swarm with minute animalculæ darting about and often exploding. Their shape is oval and contracted in the middle by a ring of vibrating curved cilia. It was, however, very difficult to examine them with care, for almost the instant motion ceased, even while crossing the field of vision, their bodies burst." From the foregoing it is evident that the water of the two localities is discolored alike by the same cause.

Those from the Gulf of California exhibited the same rapid to and fro motion as the ones seen by Darwin, and this motion was succeeded by a rotatory movement on the longer axis. Sometimes the rupture took place as soon as the latter motion ceased, and at other times the animal was motionless for a few moments preceding its final dissolution; and it was during these intervals of quiescence, only now and then observed, that anything like a correct impression of its general outline and structure could be gained. The following is the result of numerous observations extending over considerable time. The animal is oval in outline, with a projecting lip at its broad extremity, fringed with cilia. The rotatory movement took place around the smaller end as a pivot, and it advanced the same end in its to and fro movements. The envelope is a transparent and, apparently, structureless membrane, and in its interior are greenish-yellow granules, or bodies with dark rims and bright centres. These bodies floated loosely in the cavity of the animal, for when it revolved they changed their places like pebbles in a revolving cask. They averaged about the 1-12000 of an inch in diameter.

According to Mr. Darwin the bursting, which generally occurred at the extremities of the body, is due to an expansion of the tegumentary covering. I can not reconcile this with the results of my own observations. On the contrary, I noticed a contraction to take place in the transverse axis of the body; its length was increased and its transverse diameter diminished; in other words, the oval form was replaced by an oblong. This will better illustrate why the rupture generally took place at one of the extremities of the body. If these observations are correct the bursting of the envelope would be the result of an active rather than a passive action. The only reasonable way of accounting for an