LABIDOSAURUS COPE 313 



occipital region. The paroccipital exists as a distinct bone. The 

 prootic, epipterygoid, and the relations of the quadrate are as I 

 have described and figured them. The small bones above the brain 

 case, which I doubtfully called the "alisphenoids," in the doubt 

 now existing as to the presence of the mammalian alisphenoid in 

 the reptiles may be called the "postoptics," the name first pro- 

 posed for them by Cope. Nor have I any emendations to make of 

 the structure of the mandible as 

 figured by me. 



Whether all the forms have 

 additional teeth on the inner side 

 of the maxillae posteriorly I can- 

 not say since in most specimens 

 the mandibles are tightly closed, 

 precluding an examination of 

 this region. Two smaller max- 

 illae, as recorded by Branson, 



„. ... Fig. 3. — Labidosaurns. Sclerotic 



possess them. The premaxilla plates En]arged< 

 has, in most specimens, three 



teeth, of which the first is the largest, and the third small. Case has 

 based a species, L. broilii, on the presence of two elongated premax- 

 illary teeth, but I think that the character is variable. The number 

 of teeth in the maxilla also is variable. In the earlier specimens I 

 could find not more than seventeen or eighteen. In that herewith 

 figured (No. 174) there are twenty-four, the posterior ones quite 

 small. Whether this difference is a specific or an individual 

 character I am not prepared to say. I am unwilling to give specific 

 names until I am assured that I know specific characters, and such 

 we do not know well in any genus from the American Permian — 

 in general I am skeptical of the "species" of all fossil reptiles. 



Nearly every skull of Labidosaurus hitherto found was fossilized 

 in a horizontal position and it has been exceedingly difficult to 

 determine the amount of depression they had suffered. Among the 

 numerous skulls now at my command there are two only which have 

 not thus been distorted. One, an unusually large skull measuring 

 eight inches in length, shows very little if any distortion. The 

 other, that herewith figured (Fig. 1), had been evenly split along the 



