HATCHER: OSTEOLOGY OF HAPLOCANTHOSAURUS 5D 
giant reptiles. ‘These enormous Cetiosauwri may be presumed to have been of 
aquatic and, most probably, of marine habits. ...” Seeley® at one time con- 
sidered representatives of the genus Bothriospondylus (Ornithopsis) as “clearly 
ornithic” and this idea suggested to him the name Ornithopsis for those reptiles. 
Osborn in his memoir entitled “ A Skeleton of Diplodocus” leans to the aquatic 
habits of these reptiles, holding that the tail is especially modified to function as a 
swimming organ and was provided distally with a “ vertical fin” ! He believes the 
chief function of the tail to have been that of a propeller to aid the animal in swim- 
ming and that it functioned secondarily as a balancing and supporting organ. 
While holding that the Sauropoda (Cetiosaurs) are aquatic and quadrupedal, he 
‘infers that they were capable of migration on land and of assuming both a bipedal 
and tripodal position, the tail when in the latter position functioning as a third 
support in conjunction with the hinder pair of legs. 
Marsh was the first to advance the aquatic habits of Diplodocus, haying con- 
sidered the position of the narial opening as suggestive of such habits. In his 
memoir on Diplodocus the present author accepted an aquatic life as that to which 
representatives of that genus seemed best adapted when considered from their anato- 
mical structure as a whole. I remarked in that connection “That I was inclined to 
the opinion that Diplodocus was essentially an aquatic animal, but quite capable of 
locomotion on land.” 
So similar in general form and anatomical characters are the different genera of 
the Sauropoda that we may consider the group as a whole as a remarkably homo- 
geneous one, with quite similar though not identical habits characterizing most if 
not all of its representatives. It would seem therefore more advantageous to discuss 
the probable habits and mode of life of the group as a whole than those of any 
particular genus. In any such discussion there are several classes of facts from 
which evidence more or less important can be obtained bearing upon the subject. 
Among these may be mentioned the following : 
1. The anatomical or osteological characters of the group. 
2. The natwre of the other associated fossils vncluding vertebrates, invertebrates and 
plants. 
3. The condition in which the remains are found imbedded in the matrix. 
A. The nature of the matrix in which the remains are found. 
Let us next consider in the order enumerated above the evidences afforded as to 
the life habits of the Sauropoda by these four classes of testimony. 
First: As to the evidence furnished by the osteological and anatomical char- 
*“ On Ornithopsis, a gigantic animal of the Pterodactyle kind, from The Wealden.’’ Annals and 
Mag. of Nat. Hist., 1870, p. 279. 
