The Sacrum of Morosaurus. 
Contributions from the Paleontological Laboratory, No. 33. 
Bie Seeley ESI ONS 
A recent paper by Prof. H. IF. Osborn on ‘‘Some Additional 
Characters of the great Herbivorous Dinosaur Camerasaurus’’* 
shows with much reason that the number of sacral vertebrae in 
the Camerasauridae is a character not valid in the separation of 
genera. This opinion I have jong had from a knowledge of the 
type specimens upon which Marsh’s genera were based. It is very 
clear that there are three typical sacral vertebrae in all the genera 
of this family, as well as in the Morosauridae, if it be a distinct 
family, all of which present very distinct points of similarity. It 
is probable, as evidencea by the separated sacral vertebrae in 
Morosaurus lentus,~ that the condition of ossification varies with 
age, the middle three uniting earliest, the first next and the fifth 
last. The slight union of the fifth might, indeed, be absent in the 
adult without affording generic or even specific characters. 
In the University of Kansas Museum there is a portion of a 
skeleton of a species of Morosaurus, doubtless W. grandis, obtained 
by the expedition of 1895, from Converse Co., Wyoming. Among 
the different bones there is a sacrum evidently in much better 
condition than any hitherto made known in the Cetiosauria, though 
not complete. It has four vertebrae united firmly, agreeing well 
with the sacrum figured by Marsh (The Dinosaurs of North Amer- 
*Bull. Amer. Mus. Nat. Hist., x, pp. 219-233. 
+The various species of this genus described so far are as follows: 
Morosaurus Marsh, Amer. Journ. Sci., xv, p. 242.1878; xvi. p. 412, 1878. 
grandis Marsh, op. cit. xv, p. 514, 1877 (Apatosaurus); xvi, p. 416, pls. v, vi, vii, Feb , 
1879, pl. xviii-Wyoming. 
impar Marsh, op. cit. xv, p. 242 1878 (this species is clearly identical with the 
preceding).— Wyoming. 
robustus Marsh. op. cit. xvi, p. 414. 1878.—Wyoming. 
lentus Marsh, op. cit. xxxvii, p. 332, 1889.—Wyoming. 
agilis Marsh, op. cit. xxxvii, p. 333, 1889.—Colorado. 
(173) KAN. UNIV. QUAR., VOL. VII. NO. 3, JULY, 1898, SERIES A, 
