74 M Arr. ORAV RFR. 



subdivisional planes. They present u great range of size, and vary in the relative 

 extent of their inner and outer surfaces. 



/. Number 15 resembles the large specimen of d, Fig. 4, Plate X, which has a 

 single acute ridge, but it is almost destitute of subdivisional planes. 



g. Numbers 16, 17, and the large specimen of Number 18, Figs. 7, 9, 11, Plate 

 IX, have crowns like the more compressed ones of d, but arc totally destitute of 

 subdivisional planes, and one of the specimens has but a single acute ridge as in /. 



h. Numbers 20, 22, 23, 35, Figs. 1-4, 10, Plate XI ; Fig. 7, Plate XIX, have 

 crowns like the preceding g, and the small one of d. 



i. Number 21, Figs. 6, 7, Plate XI, has the crowns as in the preceding, but 

 strongly striated, and with a disposition to form subdivisional planes. 



j. Numbers 24, 28, 29, Fig. 11, Plate XI, have crowns intermediate in character 

 with the more compressed ones with subdivisional planes of d, and the two ridged 

 ones of g without subdivisional planes. 



k. Numbers 25, 26, 27, Figs. 12, 13, Plate X, have compressed crowns, nearly 

 equally divided by acute ridges, and with the surfaces subdivided into planes, like 

 the compressed crowns of d, but they are smaller. 



I. Number 30, Figs. 14, 15, Plate X, have demiconoidal crowns, with the inner 

 surface of less extent and convexity than the outer, the reverse condition usually 

 observed in Mosasaurus. They perhaps indicate a different genus from the true 

 Mosasanrus. 



m. Numbers 32, 33, 34, Figs. 16, 17, 18, 19, Plate X, are small forms interme- 

 diate to those of e and Jr. 



n. Number .'){i ' i;;. 14, Plate XI, exhibits teeth with crowns decidedly peculiar. 



Iflacrosatirus lacvin. 



Macrosaurus l(svls, OwEN, Jour. Geo. Soc, Lond. 1849, V, 380. 

 Maerosaurus, Emmons, Report North Carolina Geol. Siir., 1858, 213, Fig. 34 n. 



In the Proceedings of the Geological Society of London, Prof. Owen describes 

 two vertebrae, forming part of a collection of fossils, from the Green-sand of New 

 Jersey, submitted to his t-xaraination by Prof. Henry Rogers.^ These vertebrae, Prof. 

 Owen states, " appertain to the proca?lian type, and in the degree of the anterior 

 concavity and posterior convexity of the centrum most resemble the vertebrae of 

 Mosasaurus. They are, however, longer and more slender ; the rjiaracter of the 

 caudal vertebrae of the Mosasaurus, with their anchylosed ha?mal arch, is well 

 known and sufficiently marked. That the vertebrae in question have not formed 

 part of a tail of a reptile, is shown by the entire absence of hypapophyses as well 

 as haemapophyses from the under surface of their centrum ; from the side of which, 

 however, a large transverse process, probably a parapophysis, has projected. That 



' Notes nil Unniiiiis (if Fossil Reptiles discovered by Prof. Henry Rogers, in Green-sand Forina- 

 t;.ai,s of X.w Jersey. I'roe. Geol. Soc. Lond., 1849, V, 380. 



