NO. 39.-1889.] ZOOLOGICAL TABLES. 



185 



well -characterised types : a (No. 24), the rat-snake type ; 

 <b (No. 45), the cobra type; c (No. 27), the tree-snake type; 

 d (No. 43), the Bungarus type ; and e (No. 16), a union of 

 types c and d in Lycodon carinatus. 



In this little table I consider my ideal as nearly as possible 

 attained ; I know of nothing more, or at least of nothing 

 useful, that can be said of the ventrals of the cobra than is 

 said under b\ i.e., well-developed, broad, smooth, sub-caudals 

 two-rowed, anal entire ; and the other six species have their 

 ventrals and sub-caudals exactly the same. Here the letters 

 and figures express, as they should always express if possible, 

 exact identity in all particulars that cannot be expressed by 

 numbers ; and at the same time refer to full descriptions. 



Scales. 



In the rat-snake (No. 24) the scales are confined to the back 

 and sides ; they are imbricate, polished, and but partially 

 or feebly keeled, and the form may be characterised as 

 lanceolate. Most of the species grouped under a have 

 the scales quite smooth. In others there are apical pits 

 on the scales, and some or all of the scales may be feebly 

 keeled, minute particulars, generally requiring a lens to make 

 them out. 



Many snakes have the scales more or less keeled. These 

 form section b, and in Tropidonotus asperrimus the scales are 

 very strongly keeled ; but there is every gradation between 

 this form and that of the rat-snake, in which some of the scales 

 are very slightly keeled. In Bungarus (No. 43) the scales 

 are smooth, but there is a larger vetebral series. In the 

 whip-snake (No. 37) the scales are very imbricate and narrow. 



This character is combined with a larger vertebral series in 

 the tree-snakes, such as No. 35 and 36, Dipsas. In the remain- 

 ing snakes there are no true ventrals ; in all the burrowing 

 snakes the scales are highly polished ; in the TJropeltidcje 

 (Nos. 5 to 9) there is a rough disc at the end of the tail ; in the 

 sea-snakes the scales are always unpolished, sometimes 



D 2 



