4o6 S. W. WILLISTON 



have figured it. The broad, outer concave surface of the occiput 

 is formed chiefly by the paroccipital — I can detect nothing of 

 the petrosal — leaving a small post-temporal vacuity above as an 

 emargination of the upper side of the bone. At what seems evi- 

 dently the junction of the paroccipital and supraoccipital there is 

 a distinct notch, from which what seems to be a sutural line passes 

 downward to join the exoccipital suture. The supraoccipitals 

 form together a plate, somewhat convex in the middle above the 

 foramen magnum, which extends upward to the under side of the 

 parietals, as in lizards, but are covered, for the most part, by the 

 loosely applied bones of the cranial roof, which descend to, or 

 nearly to, the upper margin of the foramen magnum, with a slight 

 notch in the middle. In one specimen they come quite to the 

 margin, in the other they terminate some little distance above, 

 owing to the greater depression of the skull roof in the former. 

 These bones are rugose on the upper surface, forming a continua- 

 tion of the cranial table. I suppose that they are the dermosupra- 

 occipitals, joining the true supraoccipitals quite as in the cotylosaur 

 Lahidosaurus; but no certain line of distinction can be seen above. 

 On the sides in each specimen a sutural line seems distinct, separat- 

 ing the bones from the lateral element, whatever it may be, of the 

 suspensorial arch. As these lines agree in the two specimens, there 

 would seem to be little doubt of their sutural character. 



I cannot be sure of the structure of the process that curves 

 downward on either side behind to cover the upper end of the 

 quadrate. Since they join broadly the outer end of the paroc- 

 cipitals behind, one would expect to find a distinct tabulare here; 

 but if so, it cannot be demonstrated from these specimens. 



With the exception of the loosely applied dermosupraoccipitals 

 it will be seen that the whole structure of the occipital region, as 

 I interpret it, resembles that of Varanus, except that the post- 

 temporal vacuity is smaller, and that the exoccipitals take no part 

 in the formation of the occipital condyle. 



The sutures of the mandible are shown very satisfactorily in 

 the two specimens, and doubtless I should have detected them in 

 my previous study of them, had I then known what to expect. 



