14 MACROSAURUS. 
subdivisional planes. They present a great range of size, and vary in the relative 
extent of their inner and outer surfaces. 
f. 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 are 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. 
1. 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 
Mosasaurus. 
m. Numbers 32, 33, 34, Figs. 16, 17, 18, 19, Plate X, are small forms interme- 
diate to those of ¢ and k. 
n. Number 36 ‘ig. 14, Plate XI, exhibits teeth with crowns decidedly peculiar. 
MACROSAURUS. 
Macrosaurus lzvis. 
Macrosaurus levis, OwEN, Jour. Geo. Soc., Lond. 1849, V, 380. 
Macrosaurus, Emmons, Report North Carolina Geol. Sur., 1858, 213, Fig. 34a. 
In the Proceedings of the Geological Society of London, Prof. Owen describes 
two vertebra, forming part of a collection of fossils, from the Green-sand of New 
Jersey, submitted to his examination by Prof. Henry Rogers.’ These vertebra, Prof. 
Owen states, ‘‘ appertain to the procelian 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 gharacter of the 
caudal yertebre of the Mosasaurus, with their anchylosed hemal 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 hemapophyses from the under surface of their centrum; from the side of which, 
however, a large transverse process, probably a parapophysis, has projected. That 
1 Notes on Remains of Fossil Reptiles discovered by Prof. Henry Rogers, in Green-sand Forma- 
tions of New Jersey. Proc. Geol. Soc. Lond., 1849, V, 380. 
