AND AVES OF NORTH AMERICA. 65 



The most perfect tooth is slender and curved, and bears much resemblance to those "f Holops obscurus. 

 The section of both root and crown circular, the latter regularly acuminate, and furnished with delicate cutting 

 ridges. Terminal half smooth, basal half with a silky striation. Fang as well as crown, strongly curved. Cutting 



ridge descending as far on the posterior, as the anterior aspect of the crown. In a fractured New Jersey tooth, I 



count three dentinal cones. In one from Maryland, four. The inner cone is weakly fluted in both, but it scarcely 



affects the form of the enamel. 



The typical tooth of this species, as compared with the T. antiqua, is more slender and curved. In a length of 



crown and fang slightly exceeding the largest of the latter, the diameters are all about one-half the same. T 



from other portions of the jaw are but litle stouter. 



In. Lin. 



Length of tooth from New Jersey, (on curve, ) 3 8. 



Diameter at base crown, 6.6 



Length of Maryland specimen 16.5 lines. Base of crown, 9 lines. 

 Miocene of New Jersey and Maryland. 



THECACHAMPSA SQUANKENSIS, Marsh. 



Sillim. Amer. Journ. Sci.Arts, 1869, p. 391. 



The enamel of the crowns of the teeth, is in this species quite rugose. The cutting edges are short, and promi- 

 nent ; the' general form cylindric and but little curved. 



Miocene of Squankum, Monmouth Co., N. J. Mus. 0. C. Marsh. 



THECACHAMPSA FASTIGIATA, Leidy. 



Crocodilus fastu/iatus, Leidy. Proc. A. N. S., Phil., 1851, 327. 

 From Eocene of Eastern Virginia. 



BOTTOSAHRTJS, Agassiz. 



The characters of this genus have never been pointed out to the knowledge of the 

 writer. In the general form of the under jaw and teeth it does not seem to differ from 

 Alligator. One character which separates it from that genus appears to be similar to 

 that which distinguishes Thoracosaurus from Gavialis, i. e., the absence of long simple 

 hypapophyses on the cervical vertebra?, and their substitution by low transverse or divided 

 elevations. It also appears that the great external foramen which separates the angular, 

 dentary and articular bones was closed up. 



BOTTOSATJRTJS HARLANI. Meyer. 



Crocodilus harlani, Meyer Palaeologica, 1832, 108. Crocodilus macrorhynchus, Harlan. Jour. Ac. N. Sci., Phil.. 

 1824, 15 (name pre-occupied). Bottosaurus harlani, Agassiz. Leidy, Cretaceous Rept. N. Am., 12-14, Tab. 



The teeth of this species are similar to those of Alligator in the short obtuse crowns. The pulp cavity is remark- 

 ably large and extends into the crown, leaving the dentine and enamel at the apex little thicker than the sides. 



Besides the remains described by Leidy, portions of a smaller, perhaps younger, individual have been presented to 

 the Academy of Natural Sciences by Dr. Ashhurst, from near Birmingham, N. J. They consist of various fragments 

 of cranium with dermal plates. A tooth is compressed, but has a short conic acute crown, such as has not before 

 been seen in this species. 



The interorbital region is strongly pitted medially, and exhibits on each side a deep, short groove. There are no 

 marked crests. 



AMERI. PHILOSO. SOC. — VOL. XIV. IT 



