MESOZOIC TIME — TEIASSIC AND JURASSIC. 



765 



(Fig. 1217), in which the skeleton is reduced to ^^ the natural size. (Com- 

 pare with Fig. 1423, page 850.) 

 Fig. 1219 represents the hind leg 



of an allied species, Laosaurus con- 1216. 



sors of Marsh, and 1219 a, a tooth. 

 ]Sfa7iosaurus agiUs^iavsh (Fig. 1220), 

 from Colorado, is the smallest of 

 known Dinosaurs, being about as 

 large as a partridge. Another spe- 

 cies, Nanosaurus Rex Marsh, also 

 from Colorado, was not larger than 

 a Fox. 



(2) Carnivorous Dinosaurs. — Fig. 

 1221 represents a restoration of Cera- 

 tosatirics nasicornis Marsh, a mod- 

 erately large species related in 

 general characters to the Megalosau- 

 rus of Europe. The name nasicornis 

 alludes to their having a horncore 

 (/i in Fig. 1222) on the nose. Owing 

 to the form of the pelvis, the body- 

 was keeled beneath ; and the exist- 

 ence of such a keel in some Triassic 

 species is supposed to account for 

 an impression sometimes found in 

 the sandstone between pairs of footprints. 



Fig. 1215, cast of brain of Stegosaurus (x J); ol, olfac- 

 tory nerves ; op, optic lobes ; on, optic nerve ; 

 cb, cerebellum ; m, medulla oblongata. Fig. 1216, 

 cast of cavity of nervous mass in the sacrum, 

 seen from above (x J); f,f',f", each foramen 

 betvreen two sacral vertebrae. Marsh. 



1217 



1217-1220. 



1218 



1219 



HEEErvoEoirs DnfOSAiiES. — Fig. 1217, re.storation of Camptosaurus dispar (x j\) ; 1218, tooth of C. medius ; 

 1219, Laosaums consors, hind leg (x Jj) ; 1219 a, tooth of same ; 1220, Nanosaurus agilis, dentary bone, as 

 seen from the left, natural size. All from Marsh. 



