690 REPORT OF NATIONAL MUSEUM, 1898. 



boas and pythons it has a short anterior process on the inner side with 

 which the columella auris articulates. The process is very short in 

 Eryx, and an articular facet only remains in Loxocemus, Lichanura, and 

 Charina. In the venomous snakes it is so elongate as to articulate 

 with the superior disk of the paroccipital, extending to the inner border 

 in the Solenoglypha. 



The base of the skull presents certain diversities in the more distinct 

 suborders. 



There is much difference as to the extent to which the free edges of 

 the presphenoid extend outside of the trabecular grooves, concealing 

 them from view from, below, or whether they are angulate or not. In 

 some genera the basioccipital supports one to three hypapophyses for 

 muscular irssertion, and in a few genera the sphenoid bone supports basi- 

 pterygoid processes or tuberosities, accompanied or not with a median 

 keel. In Solenoglypha the long median simple hypapophysis is con- 

 stantly present, and in the Peropoda there are nearly always basi- 

 pterygoids. Beyond this these characters are specific only, or connected 

 with the size and vigor of the individual. The following table will 

 show this : 



I. No basioccipital hypapophysis. 



a. Basipterygoid processes. 

 p. A median sphenoid keel. 



Python, Boa. 

 (3/3. No median sphenoid keel. 

 Loxocemus, Eryx, Causus. 

 aa. No basipterygoid s. 



Typhlops; Lichanura, Charina; Cylmdrophis; Xenopeltis; Carphophiops, 

 Cemophora, Ahastor, Osceola, Storeria, Begina, Salvadora, Liopeltis, 

 Cyclophis, Coluber (guttatus); Hydrophis. 



II. Three hypapophyses. 



a. The median largest; Eutcenia marciana. 



aa. Thft lateral largest (weak) ; Eutcenia proxima, Ophibolus sayi (strong), 

 Zamenis constrictor, Z. flagellum. 



III. Two hypapophyses, 



(Freak); Ilysia scytale, Elaps fulviua. 



IV. One hypapophysis, flat below, 



Compsosoma corais, Eutwnia sirtaUs, E. saurita. 

 Y. A long compressed hypopophysis. 



Vipera, Ancistrodon, Sistrurus, Crotahts. 



The palatine bones differ considerably in the principal forms. The 

 characters are seen in the presence or absence of the external (maxil- 

 lary) or internal (vomerine) processes. These may be tabulated as 

 follows: 



I. Internal and external processes present. Colubridse, Xenapeltidae, 

 Charina, Python (the internal small), Glanconia. 



II. External process, but no internal. Boa, Eryx, Loxocemus, 

 Lichanura. 



III. Internal, but no external processes. Elaps, Typhlops. 



IV. Neither internal nor external processes. Hydrophis, Causus, 

 Vipera, Ancistrodon, Crotalophorus, Crotalus. 



