CROCODILIANS, LIZAKDS, AND SNAKES. 



177 



the types of affiuity with the extinct types have scaly heads; for 

 instance, the Sjyhenodon of the Tihynchocephaliau order is approached 

 closely in scale characters by the Pachygloss lizard. The ]>oida*, 

 among snakes, recognized as the most primitive forms, also have 

 generally scaly heads and few or no plates. The scaly head also char- 

 acterizes some of the higher types of snakes, as many Solenoglypha, 

 as well as the degenerate Epanodonta and Oatodonta; while most of 

 the degenerate Sauria have head plates, but more or less fused. 



f^N^i- {- ^ 



Fig. 3. 

 UE-IAILS UF EUMECE8 yUINQUELINEATUS LiNN.EOS (femalf) 

 Cat. No. a;)53, U.S.N. M. 



Fig. 4. 

 Details of Osceola doliata syspila Cope. 



Cat. No. 1,^361, U.S.N.M. 



/i', rostral plate ; l;i, iuternasal ; J/'u, intorfrontouas.al; Pc/, prefrontal ; /•', Croiital; .Voc, supraocular; 

 /■>, frontoparietal; J', p.ariotal; //', interparietal; Oc, occipital; M, mental; I'M, postmental; laL, 

 iufralabial; aV, nasal; Pi, prelore.il; X, loreal; /Sc, superciliary; T, temporal; i9)/, symphyseal; O, 

 genial; Peo, preorbital; I'so, postorbital; PrA, preanal; Ga, gastrosteges (scuta); Ur, urosteges 

 (scutella). 



The nomenclature of these plates is explained on the above cuts of 

 the heads of a Scincoid lizard and a Colubrine snake. 

 NAT MUS 98 — 12 



