AND THREE ALLIED NEW GENERA. 7 



The tooth figured in PI. I. Fig. 4 has the Mosasaurus form, as described by Owen 

 and figured by Faujas St. Fond, and was received from an unknown locality in 

 Alabama. It is solid, and shows the lamellar arrangement very distinctly. A 

 similar tooth from Georgia is figured in PI. I. Fig. 5. 



Their size, taken in connection with the existence of vertebrse which have all the 

 characters of maturity, and evidently belonged to a small individual, disposes me to 

 consider them as characterizing another species, which may be called Mosasaurus 

 minor. 



The vertebra from Wilmington, North Carolina, (PI. I. Fig. 6,) appears identical 

 with those found in New Jersey, now in the Academy of Natural Sciences. This 

 seems the most common species, as I have seen similar vertebrae in the cabinets of 

 Professor Agassiz and of Dr. J. C. Warren, from New Jersey ; and I have fragments 

 of others from Alabama. 



My friend. Dr. S. G. Morton, placed in my hands two teeth of Mosasaurus from 

 the Cretaceous deposits of the banks of the Chattahoochie, Georgia, discovered by 

 J. Hamilton Couper, Esq., which differ from all the described species in their 

 greater compression posteriorly, and in the sharpness and extent of the cutting 

 edges, with a curve backwards giving them the form, on a lateral view, of the 

 teeth of Megalosaurus. (PL II. Figs. 4, 5.) In honor of the discoverer, a gentle- 

 man who has made many valuable contributions to the science of our country, I 

 propose to name this species Mosasaurus Couperi. 



The portion of a lower maxilla sent me by Chancellor Dargan is interesting 

 from its geological position. It is reported as found with cetacean remains among 

 the shells of the Pliocene. In Darlington, as the beds of Pliocene rest upon the 

 Cretaceous, it is most probable it was derived from the latter formation. Its 

 appearance and the mineralization of its structure render it probable that it came 

 originally from the Cretaceous. I have, from the same Pliocene beds, teeth of 

 Crocodilus davirostris, Morton, (of which Professor Agassiz proposes to form a new 

 genus Sphenosaurus,) which in New Jersey is found in the Cretaceous. 



The specimens found in Europe are all from the Cretaceous, as well as those from 

 Missouri, Alabama, and New Jersey, while the vertebra from Wilmington was 

 found in the Eocene, as well as those from the marl of Ashley River, South 

 Carolina. From the latter locality I have many vertebrse of Basilosaurus ; ribs 

 and vertebrse of Manatus ; a tooth of Equus resembling E. plicide7is, Owen ; teeth 

 of Crocodilus macrorhynchus, Harlan ; and of Conosaurus, about to be described. 



The fragment of the jaw of Mosasaurus above mentioned is seven inches in ■ 

 length, and constituted a portion of the anterior part of the lower maxilla of the 

 right side. The figures PL II. Figs. 1, 2, 3, represent it of the natural size. At 

 the lower outer edge are two large foramina, as in M. Hoffmanni and in M. 

 Maximiliani. Examined on the inner aspect, (PL II. Fig. 3,) we find it is only 

 the portion external to the groove or alveoli for the insertion of the bony roots of 

 the teeth. The base of a tooth, with the pulp cavity, is present, surrounded by 

 enamel, invested by its osseous oblong support, obliquely inserted ; and the alveolar 

 surface of attachment of three others is distinctly marked. Here is also seen, on 



