524 S. IV. WILLI STON 



squamosal suture, the outer side of the quadrato-jugal, forming 

 the anterior superior boundary of the lower temporal vacuity. 

 In Ornitliostoma it very clearly unites above with both the 

 quadrato-jugal and postfrontal, and in all probability the same 

 relations obtain in Nyctodactylns, but of this I am not sure. 



The supratemporal bar is evidently formed of two bones, as 

 in Ornitliostoma. The superior one, joining the outer angle of 

 the frontal (and parietal), is clearly the postfrontal or post- 

 fronto-orbital. It extends backward to the head of the quad- 

 rate, also touching the squamosal, and probably also joining the 

 jugal, as in Ornitliostoma. The inferior outer part of the bar, 

 uniting with the jugal, as described, anteriorly, the head of the 

 quadrate, and apparently also the squamosal posteriorly, is, I 

 suppose, the quadrato-jugal, though it corresponds precisely in 

 position and relations with the bone I have called the pro- 

 squamosal in the mosasaurs, following Baur. This bone in these 

 and other lacertilians has, at various times, been called the pro- 

 squamosal (Baur, Williston), the quadrato-jugal (Gegenbaur, 

 Merriam,. Baur), the squamosal (Owen, Huxley, Cope, Baur), 

 and the supratemporal (Cope). In this pterodactyl the bone 

 does not descend to separate the jugal from the quadrate. 

 This, according to Seeley, is sometimes the condition among the 

 pterodactyls. If so, the element must surely be the quadrato- 

 jugal, and not the prosquamosal. 



The squamosal seems clearly defined. It is a triangular, curved 

 bone. A small process runs forward to join the post-frontal 

 and " quadrato-jugal ; " a broader and flat one curves down- 

 ward and inward to join the wing-like squamosal process of the 

 parietal, forming the parieto-squamosal arch, while a third joins 

 the opisthotic (paroccipital), and probably also the head of the 

 quadrate. It thus helps to form a small vacuity on the occipital 

 region, between the opisthotic, parietal, and squamosal — the 

 supraoccipital vacuity. It has nothing to do with the brain- 

 case, as Seeley thinks it has in the European forms. 1 



The occipital condyle forms something less than a hemi- 



1 Seeley, Dragons of the Air, London, 1901. 



