GEOLOGICAL SURVEY OF THE TERRITORIES. 401 



in the continuation of the same yellow chalk formation in the Territory 

 of New Mexico, and will probably be found in Colorado and Kansas. 



The genera to which these species belong are Clidastes, Cope, Liodon, 

 Owen, and Mosasaurus, Conybeare. The two latter occur also in the 

 cretaceous strata of Europe. While Mosasaurus is most abundantly 

 represented in the cretaceous of the eastern parts of the United States, 

 Liodon abounds much more in the central regions. 



MOSASAURUS, (CONYBEABE.) 



MOSASAURUS MISSURIENSIS, (HARLAN.) 



(Ichthyosaurus do., Harlan, Trans. Amer. Philos. Soc, IV, 405, Tab. XX, 1834. Batra^ 

 chiosmirus, Harlan. JBatrachiotherium, Harlan. ? Mosasaurus neovidii, Meyer. ? M. 

 maximiliani, Goldfuss. M. missouriensis, Leidy, Cretac Eept., 1865. PI. VII, figs. 15, 16, 

 17,18.) 



The centra of the vertebrae of this species are moderately depressed. 

 The centra of the caudals, posterior to the disappearance of the dia- 

 pophyses, are as wide as deep, and of nearly similar length, and with 

 anchylosed chevron bones. A fine cranium figured by Goldfuss shows 

 the crowns of the teeth to be subcylinclric, incurved, and facetted; 

 but it is not certain that it belongs to this species. 



An unusually perfect specimen of this species, or one allied to it, was 

 recently exhumed by W. E. Webb, near the town of Topeka in Kansas. 

 My friend Professor J. Parker, of Lincoln College, of that place, informs 

 me that it is seventy-five feet in length, and the gentleman who discov- 

 ered it, that it measures eighty feet. Its mandibular rami are stated by 

 the same person to measure five feet. Measurements of the vertebrae 

 indicate them to be of a size quite similar to those of large individuals 

 which have been discovered in the green-sand of New Jersey. They 

 measure as follows, as stated on photographs by my friend W. E. Webb : 



Inches. 



Diameter cervicals centra only : 2.5 



Diameter dorsals, with diapophyses 7 



Diameter lumbars 2 



These proportions illustrate again the Ophidian or eel-like form of this 

 genus, and the relatively large size of the head. 

 The teeth resemble in size those of large specimens of ill. delcayi. 



LIODON, (OWEN.) 



(Proceed. British. Assoc. Adv. Science, 1841, p. 144. Cope, Trans. Amer. Philos, Soc, 



1869, p. 200.) 



This genus is characteristically American ; four species are known from 

 the western cretaceous, four from the eastern, (L. mitchillii, L. validus, L. 

 sectorius, and L. laevis,) and two from the southern, (L.perlatus&n&L.cong- 

 rops ;) one species (L. ancepsj is British. Some very large species (L. dyspe- 

 lor, L. proriger) belong to it, while L. congrops is one of the smallest of the 

 order. 



LIODON PRORIGER, (COPE.) 



(Transactions Amer. Philos. Soc, 1869, p. 202. Tab. XII, Figs. 22-24. Hacrosaurus 

 proriger, Cope, Proceed. Ac. Nat. Sci., Phil., 1889, p. 123. Leidy, Cretac. Rept. II, 

 15, 16, [caudal vertebra.]) 



The history of this large Mosasauroid was originally based on material 

 in the Museum Comparative Zoology, Cambridge, Massachusetts, brought 

 26 g 



