4 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63. 



below the frontal surface, for the reception of a nasal. The shape 

 of this area suggests that the nasals must have been very narrow, 

 closely approximated, and slightly widening anteriorly. The sinuses 

 on the superior face of the frontal for the reception of the nasals, 

 as discussed above, occupy a sloping surface 34 mm. long, 17 mm. 

 wide proximally, and 23 mm. wide distally. The sutures are shallow 

 posteriorly and become deeper anteriorly. At either side of the 

 nasal sinuses appears a similar depre^^ion for the ascending process 

 of the premaxilla, whose maximum width is about equal to that of 

 the base of the nasal. External to these sinuses for the premaxillae 

 there are eight or more grooves for lodging the posterior ends of the 

 maxillse. Each of these grooved areas is approximately 33 mm. 

 wide and beyond these the surface of the frontal is relatively smooth. 



The supraoccipital is very broad at the base and its sides curve 

 obliquely upward; in consequence the apical portion is pointed and 

 not rounded as in Agor-ophius pygmams. There is a well defined 

 carina on the apical portion of this bone, on either side of which the 

 surface is slightly depressed. These depressed areas on the apical 

 half of the supraoccipital probably afforded an extensive area for 

 the attachment of the muscles which assist in raising the snout. 

 The condyles do not project beyond the plane of the exoccipitals. 

 The squamosals and their slender zygomatic projections form the 

 posterior and outer margins of the temporal fossae. Both zygomatic 

 processes are incomplete anteriorly, but it is doubtful whether they 

 were originally in contact with the postorbital projection of the 

 supraorbital plate of the frontal. 



Posterior view. — As a whole this view narrows toward the vertex 

 from the postglenoid processes of the squamosals. As seen from this 

 aspect the supraoccipital curves upward and forward. The lamb- 

 doidal crest, formed by the lateral margins of this bone and the 

 abutting edges of the parietals and squamosals, is well marked and 

 becomes more prominent toward the apex. The supraoccipital is 

 broadly sutured to the parietal as is shown by the exposed edge of 

 the parietal (pi. 2) which at this point is 26 mm. wide. 



The exoccipitals are relatively small, coalesced with the supra- 

 occipital above, and projecting outward and backward. Anteriorly 

 they are suturally united with the squamosals while inferiorly they 

 are fused with the basioccipital. A somewhat similar arrangement 

 of the bones comprising the basicranium is shown by Cetotherinm 

 megalophysum^ but in this form the exoccipitals do not extend back- 

 ward beyond the condyles, although they are produced downward 

 below them. 



The opening for the foramen magnum is almost circular. The 

 occipital condyles are semielliptical in outline, considerably broader 

 near the base than near the apex, and slightly convex from side to 



