Genus Lysoroplius, Cope. 237 



is that in the drawinj; of the American specimen the ex- 

 occipital is re[)rescntecl as very small. Tliis is, I think, wrong, 

 the exoccipital being large, as represented in the drawing 

 of the Tubingen specimen. The drawing v. Huene gives 

 of the occipital condyle is thoroughly satisfactory, showing 

 that the articulation is as much basi- as exoccipital. 

 Von Huene's identifications of the fenestra ovalis and fora- 

 men for the vagus are probably correct. 



The large bone situated by the sides of the supraoccipital 

 has been very variously identified. By Broil i and Case 

 they have been called squamosals, by Williston epiotics, and 

 by V. Huene supratemporals. That they cannot be squa- 

 mosals requires no argument, the undoubted squamosals 

 lying in front. Nor can they, I think, be regarded as 

 supratempor;ils. From their l>eing quite behind the parie- 

 tals, and at the sides of the supraoccipital and far behind 

 the jaw, it is very doubtful if they in any way roof the 

 temporal region. They may be epiotics, but we do not 

 know any forms in which epiotics take up this position. 

 They further appear to overlap the supraoccipital, and to 

 be thus mertibrane bones. It seems to me that they, how- 

 ever, answer all the requiren)ents of the tabulares. They 

 lie on the outer part of the paroccipitals, are behind the 

 parietals, and articulate with both the parietals and squa- 

 mosals, and to form the upper lateral parts of the occiput. 



The lower jaw has never been fully described. Von Huene 

 figures one of the specimens in the American Museum, but 

 with one or two of his interpretations 1 do not agree. He 

 has also examined some jaws in the Tiibingen Museum, but 

 they have apparently not yielded any fresh light. The 

 American Museum specimen, no. 4761, shows something of 

 the jaw, but not nearly so much as two other specimens not 

 nuudjered. Between these three specimens practically all 

 details can be made out (fig. 2). 



The dentary forms about two-thirdsof the jaw. It comes 

 to a sharp point in front and forms with its neighbour a 

 short feeble symphysis. It articulates on the outer side 

 behind with the surangular and angular. The splenial is a 

 small bone lying on the inside of the lower part of the 

 dentary just behind the symphysis. It forms the lower 

 margin of the jaw in this region. The angular forms nearly 

 the whole of the lower border of the jaw, passing in front 

 between the dentary and the splenial. From two of the 

 American Mus^eura specimens I incline to differ from 

 V. Huene, and believe that the splenial does not form part 



Ann. (t- Ma(/. JS\ Hist. Ser. 9. Vol. ii. 18 



