194 



MAJOR F. WALL, I.M.S., O.M.Z.S. 



Key to the Genus Distira. 



A. Ventrals present ; anterior three to four times breadth of last costal row. 



(See fig. 57) . . . . . . . . . . viperina. 



B. Ventrals present; anterior not more than twice breadth of last costal row. 



(See fig. 38). 



(a) Scales in midbody 19 to 21 .. .. .. .. jerdoni. 



(b) vScales in midbody more than 21. 



(a 1 ) Ventrals with median suture or furrow in posterior half of body. 

 (See fig. 13). 



(a 2 ) Praefrontal touches second supralabial, but not third. 



Anterior costals 17 to 21. Ventrals 225 to 298 .. gracilis. 



(I/ 2 ) Praefrontal touches third supralabial (rarely second also). 



Anterior costals 21 to 25. Ventrals 377 to 474 . . cantoris. 



(b 1 ) Ventrals unfurrowed; a few posterior irregularly divided, es- 

 pecially about umbilical scar. 

 (<; 2 ; Posterior costals juxtaposed (except rare examples of fasciata 

 and some torquata). 



I a' 6 ) One or more marginals. 



(a 1 ) One large anterior temporal. 



(a 6 ) Anterior costals 1 to 9 less than posterior . . torquata. 

 (b b ) Anterior costals 10 to 22 less than posterior fasciata. 



(A k ) Two small superposed anterior temporals. 



(a b ) Anterior costals 25 to 29 ... . . mamillaris. 



(b b ) Anterior costals 31 to 37 ; parietals touching 



postocular . . . . . . lapemoides. 



(c b ) Anterior costals 36 to 45 ; parietals not 



touching postocular . . . . coerulescens . 



(// b ) No marginals. 



(a 1 ) Anterior costals 29 to 41 . . . . ornata. 



(&*) Anterior costals 45 . . . . . . ocellata. 



(b % ) Posterior costals imbricate or sub-imbricate (except rare 

 examples of coerulescens and some torquata). 



(rt s ) Anterior costals 19 to 23. Neck ] to £ greatest body 



depth . . . . . . . . obscura. 



(6 b ) Anterior costals 23 or more. Neck \ to | greatest 

 body depth. 



(a*) Ventrals 250 or less . . . . . . major. 



(/> l ) Ventrals 270 to 375. 



(a b ) Costals in midbody 29 to 36. One large 

 anterior temporal. Praefrontal touching 

 2nd labial . . . . . . spiralis. 



(b b ) Costals in midbody 33 to 44. Two super- 

 posed anterior temporals. Praefrontal 

 touching 2nd labial . . . . cyanocincta. 



