HATCHER: OSTEOLOGY OF HAPLOCANTHOSAURUS oul 
what family of the Sauropoda it pertained, although Owen’s statement that the 
transverse diameter of the centrum exceeds the vertical together with the broad, 
almost flat inferior surface and other characters indicated by the figures would seem 
to fix this centrum as pertaining to a median cervical of some member of the Moro- 
sauride. 
Comparison of Haplocanthosawrus with Bothriospondylus Owen. 
A comparison of the various characters exhibited by the species of Bothriospon- 
dylus described by Owen in his Monograph on that genus published as part II., of his 
Reptilia of the Mesozoic Formations, pp. 15-26, Plates III.-IX., will show many strik- 
ing resemblances to Haplocanthosaurus and at first sight one might be led to believe 
that they pertain to the same genus as that to which the material under discussion 
pertains. A closer examination however will reveal several striking and important 
differences certainly to be regarded as 
of generic if not of family rank. Such 
distinctive characters are especially ob- 
servable in the sacral centra as will be 
seen by a comparison of Fig. 20 show- 
ing side views respectively of the fourth 
and terminal sacral centra of the type of 
Haplocanthosawrus utterbacki with the 
figures on Plates III. and IV., of the 
monograph just cited. As will be seen 
Fig. 20. 
by an examination of Owen’s figures and 
text the median sacrals of Bothriospon- Fig. 20. 4. Centrum of fourth sacral of Haplo- 
4 Y canthosaurus utterbacki seen from right side (No. 879). 
dylusare provided with both anterior and 2 © ) 
5. Same view of fifth or last sacral centrum of same. 
posterior parapophysial facets, while in goth + natural size. 
Haplocanthosaurus as shown in Fig. 20, 
there is but a single facet, which in the centrum of the fourth sacral is median in 
position antero-posteriorly, but somewhat elevated above the median longitudinal 
line. Furthermore the pleurocentral cavities so conspicuous in the sacral centra of 
Haplocanthosawrus beneath the parapophyses are entirely wanting in Bothriospon- 
dylus. The cavities in the sacrals of that genus shown at f, Plate III., Figs. 2 and 
4, and Plate IV., 4 and 5, of Owen’s Monograph lie above the parapophyses and are 
not homologous with the pleurocentral cavities. These characters as well as others 
of only less importance are quite sufficient to distinguish Huplocanthosaurus from 
Bothriospondylus, 
