2 20 Bulletin American MuseufH of Natuial History. [Vol. X, 



Third. — The observation of structural analogy to certain stru- 

 thious birds in the anterior dorsals and posterior cervicals. 



I. Habits and Size of the Animal in Relation to Its 

 Structure. 



The estimate given by Marsh of the total length of this animal 

 is nearly or quite 60 feet ; the tail is figured at about 24 feet. 

 Since the vertebra believed by Marsh to be the third caudal is 

 probably the loth or nth, the tail should be increased to over 30 

 feet in length, by the addition of at least seven large anterior 

 caudals. The total number of caudals is estimated at 40 as 

 against 37 in Diplodocns. Marsh has attributed to Brontosaitriis 27 

 precaudal vertebrae, or 13 cervicals and 14 dorso-lumbars. From 

 reasons given below it is probable that there was a larger number 

 of dorso-lumbars, which would still further increase the length of 

 the animal to considerably over 60 feet. 



We can only conceive of the Camarasaur as a great wading and 

 swimming quadruped, enjoying a habitat similar to that of the 

 Upper St. John River, Florida, at the present time, namely, a 

 relatively firm bottom gently graded to all depths, supporting a 

 richly luxuriant aquatic vegetation, the river banks bordered by 

 sloping shallows of sand (Colorado, Caiion City Beds) or clays 

 (Wyoming, Como Beds). As imagined by Cope in his picture of 

 Amphicalias ('Century Magazine,' November, 1887), the animal 

 could walk along the bottom, raising the anterior portion of its 

 body. We believe also that it could swim rapidly, propelled by 

 its light but long and powerful tail, which would be useless 

 upon land. The abundance of cartilage around all the limb 

 joints and the non-osseous nature of many of the carpals and 

 tarsals afford positive evidence that the limbs were not con- 

 tinuously subjected to the hard impact of the enormous weight 

 of the body by motion on land. Feeding was done in the 

 water and along the shores. Excursions upon shore were there- 

 fore like those of the Alligator, mainly for breeding and egg- 

 laying purposes, and they exposed the animal to attack by the 

 Megalosaurs. By means of powerful mid- and posterior-dorsal 

 spines and opisthocoelous vertebra, the entire anterior part of the 



