THE CLASSIFICATION" OF THE OPHIDIA. 197 



ous Ophidia. Huxley called the paroccipital of the Reptilia the opisthotie, hence in 

 my first determination (in 1871) I used the latter term for it in the Ophidia. 



A. Paroccipital intercalated in the cranial walls (Angiostomata). 



* No ectopterygoid ; palatines bounding choanse posteriorly ; ethmoturbinal forming part of roof 

 of mouth ; rudiments of pelvis ; two lungs. 



I. Maxillary bone fixed to prefrontal and premaxillary ; a pubis Catodonta. 



II. Maxillary bone vertical and free from all others ; no pubis Epanodonta. 



** An ectopterygoid ; palatines not bounding choante posteriorly. 



III. Maxillary bone free, horizontal Toktricina. 



B. Paroccipital attached scale-like to cranial walls and produced freely ; ectopterygoid present 



[Eurystomata). 



IV. Maxillary bone horizontal, not forming a ginglymus with prefontal Colubrotdea. 



V. Maxillary bone vertical and articulating with the prefrontal by a ginglymus ; a tracheal lung. 



SOLENOGLYPHA. 



Within these suborders the pulmonary characters define superfamilies and families. 

 The penial characters, as already remarked, have various values, generally defining 

 subfamilies and genera or groups of genera. These are given in the analytical tables 

 under the family and subfamily heads. On examining these tables it will be seen that 

 the genera brought into close juxtaposition are frequently not most closely allied in 

 general appearance. The keys are chuflij intended to 'present the penial characters, and 

 do not always display the serial or other relationships of the genera among themselves. 

 The intimate filiations of the genera among themselves are not yet sufficiently Avell 

 known to make it possible to do otherwise at present. 



EPANODONTA. 



I have nothing to add to what has been already stated regarding this suborder 

 (p. 191). 



CATODONTA. 



What is known of this suborder has been already mentioned (p. 191). 



TORTRICINA. 



In Ilysia the hemipenis is deeply bifurcate and the surface of each branch is flounced. 

 The flounces are oblique to the sulcus and are spineless. Below the bifurcation the 

 surface is smooth, excepting a wart (Plate XIV, Fig. 1). 



COLUBROIDEA. 



Five well-marked divisions are embraced in this suborder, as follows : 



I. Chevron bones open inferiorly. 



Rudimental pelvis and posterior limbs ; no grooved teeth ; generally two lungs Peeopoda. 



No rudimental pelvis or limbs nor grooved teeth ; one lung rudimental Aglyphodonta. 



