FOSSIL LIZARDS FROM "WYOMING — GILMORE 



73 



tions it has been restored following modern iguanids. The lachrymal 

 is very small and in line with the jugal. The large jugal is without 

 a posteriorly directed spur. Only the right quadrate is present, and 

 it is so damaged that its detailed structure is obscured. As depicted 

 in figure 31 it may be too short. It appears to have a nearly straight 

 external border. The top of the supraoccipital is not wholly beneath 

 the overlying parietal but is visible from above as shown in figure 

 30. A low obtuse vertical ridge extends upward from the top of the 

 foramen magnum. The supraoccipital is fully coalesced with the 

 exoccipital. The occipital condyle is plain and without evidence of 

 participation of the exoccipitals. 



The basioccipital and sphenoid surfaces are confluent. Basiptery- 

 goid processes are large, with spatulate ends directed strongly for- 



pmx. 



Figure 31. — Skull and lower jaw of Aci-pricn formosum Cope (U. S. N. M. No. 16566), 

 viewed from the left side: co, Coronoid; d, dentary;/, frontal; ju, jugal; qu, quadrate; 

 la, lachrymal; mx, maxillary; na, nasal; p, parietal; pmx, premaxillary; poc, paraoccipital; 

 pof, postorbital; prf, prefrontal; sq, squamosal. About three times natural size. 



ward. There is no evidence of teeth on the pterygoids. The other 

 palatal elements are so badly disarranged as to furnish no reliable 

 information regarding the true structure of the palate. 



Lower jaw. — The mandible in specimen U.S.N.M. No. 16566 is rep- 

 resented by the right dentary, with full dentition posterior of the 

 coronoid process and the greater portion of the left dentary lacking 

 most of the teeth. These contribute but little new information, and 

 since the lower jaw has been described in a previous publication there 

 is no reason to repeat it here. The dentary carries 25 closely set teeth 

 in the complete series. In the restoration of the missing part of the 

 ramus in figure 31, the very complete ramus forming part of the type 

 of Aciprion majus was used as a guide. 



Dentition. — The dentition is pleurodont, the dental formula being 

 premaxillary 6, m.axillary 20, dentary 25. The teeth are closely 

 placed, cylindric with compressed crowns. The latter support a large 



