JURASSIC VERTEBRATE FOSSILS. 489 



Their distal ends are firmly coossified, forming a powerful support for the 

 ilium. Between these processes are large, oval openings, as shown in fig. 33. 



The present remains indicate that this reptile when alive was about 

 50 feet in length. Its general form and proportions were very similar to 

 those of Brontosaurus, an allied genus, the skeleton of which is represented 

 in the restoration on PI. XXI. 



In the same series of strata, a few miles to the south, and just above 

 the village of Morrison, various remains of a much larger species of the 

 same genus were found in the following year, and described by the writer 

 as Atlantosaurus uiniuni'is. A femur belonging to the type specimen is 

 represented, one-sixteenth natural size, in figs. 34 and 35. 



The other remains of this enormous reptile recovered show many 

 points of interest to anatomists, which will be discussed fully by the 

 writer elsewhere. It may, however, be stated that the head of this animal 

 was quite small, and the neck very long and lightly built, insuring great 

 flexibility. The vertebra^ of the trunk wen- also lightened by large cavi- 

 ties in the sides, similar to those in the sacrum. The tail was powerful and 

 much elongated. All the limb bones were massive and solid. The animal 

 was herbivorous in habit, and its food was probably soft, succulent vegeta- 

 tion, which it obtained along the borders of the great fresh-water lake in 

 which it was finally entombed. When alive, it was about 70 feet or more 

 in length and 20 feet in height. 



APATOSAURUS. 



In the same stratum with the Atlantosaurus fossils the bones of an 

 allied genus, Apatosaurus, were also found by Professor Lakes, and 

 described by the writer in 1S77. This reptile, although somewhat smaller 

 than the one last described, was of gigantic dimensions, and similar in 

 habit. A neck vertebra of one species is shown in fig. 3G. The sacrum of 

 the type specimen, represented one-tenth natural size in fig. 37, has but 

 three coossified vertebra', thus differing from that of Atlantosaurus. The 

 pelvis of the same individual is shown in fig. 38, and this is typical of the 

 group. 



The cervical vertebrse of Apatosaurus are strongly opisthocoelian, and 

 of moderate length. The dorsals have their centra similar, and both have 



