CROrODILIANS, LIZARDS, AXD SNAKES, 183 



sary that a new survey of the subject shouUl be made. In 185G the 

 Zootomie der Amphibien, by Stanuius, appeared. The account of the 

 osteology of lizards given in this work is more complete than that of 

 Cuvier, but it is incomplete in many jjoints, and is not up to the require- 

 ments of the present time. The present study is made with especial 

 reference to the necessities of the paleontology of the order, therefore 

 the description of characters is made as specific as jiossible. The 

 principal novelty will be found in the references to North American 

 genera and in the descrii)tions of the hyoid aj^paratus. The descrip- 

 tion of the scapular and pelvic arches in certain genera with the 

 extremities degenerate or wanting, where they have not been previ- 

 ously described, is contained in a separate illustrated paper, which has 

 been published.' 



Skull. — The premaxillary bone is single, except in the Scincidte, Acon- 

 tiida^ and some Geckonidse {Phyllurus sp.). It is very small in the 

 Iguanid genus Phrynosoma, and in the Agamidie it is excluded from 

 contact with the vomer by processes of the maxillaries, which meet ou 

 the middle line. In the Chama'leouidfie the premaxillary is still smaller, 

 the body being narrower than the superior spine, and sui)porting but 

 one tooth. In the Anguidae the premaxillary is bounded posteriorly 

 on each side by a foramen which is sometimes large, but is wanting 

 in other families, including the Helodermidte. In Lcpidostermim it is 

 principally on the inferior face of the muzzle. The nasal bones are gen- 

 erally distinct, but in the Yaranidie they are fused into a single nar- 

 row median element. In the ChamaBleonidtii they do not attain the 

 nasal border, being cut off by the junction of the prefrontal with the 

 premaxillary and maxillary bones. In the genus Feylinia the nasal 

 bones are fused into a broad plate. In Lejndostenmm they are com- 

 pletely cut oft' from the nasal border by the maxillary, which is broadly 

 in contact with the i^remaxillary spine. In RMneiira the nasal bone 

 reaches the nares, as in AmphLshcena. The frontal bones are separate 

 in the Yaranidii^, Helodermid.e, Anguidjii, Scincid;e, Anelytropsidoe, 

 Anniellidrt', and Ami)hisbienida', and in some GeckonidiB. They are 

 coossified in some Geciionidiej in the Iguanidte, Agamidai, Xenosau- 

 rida), Eublepharid;c, Chamadeonidie, and Teiida*. The parietals are 

 generally fused, the only exception being the Geckonidie, Uroplatidae, 

 and Xantusiidu'. Prefrontals are always present, and in Anniellida.', 

 Helodermida', and Gliamadeonidai they extend posteriorly to the post- 

 froutals, excluding the frontal from the orbital border. Lachrymals 

 are i)res(Mit, but tliey are fused with the prefrontal in the Scincidie. 

 The jugal is generally present, even when there is no postorbital arch, 

 as in Geckonida^, where it is a splint; but in the Amphisbania, 

 Annielloidea, and in Feylinia, the splint-like element attached to the 

 maxillary extends to the pterygoid posteriorly and the prefrontal 

 anteriorly, and may include the lachrymal. The jugal extends ante- 

 riorly as far as the lachrymal except in the Sciucidai. The postfrontal 



•Journal of Aloipbyology, VII, 1892, p. 223. 



