Mr. N. Rosen— Repb/ to Mr. G. A. Boalenger. 



121 



Anisodon Lilljeboryi (of which 

 there are two specimens of 

 exactly the same shajje, one 

 larger than the other). 



(1) Hypapophysespresentthrough- 

 out the vertebral columti, represented 

 on the posterior dorsal vertebrce by a 

 well-developed crest, p)rojecting beluw 

 the condyle. 



(2) At least 13 maxillary teeth. 



(3) Of the maxillary teeth the 

 fourth and fifth enlarged. 



(4) The last tivo maxillary teeth 

 much enlarged and grooved. 



(o) Rostral distinctly visible from 

 above. 



(6) Frontal 7iot twice as long as 

 broad. 



(7) Temporals 2+2. 



Psammodynasfes pulverulent us, 1 Joie 

 (according to Mr. Boulenger'a 

 description). 



(!) Hypapophyses absent on the 

 posterior dorsal vertebrce. 



(8) Snout pointed. 



(9) A dorsal series of rather 

 large lighter spots, edged with 

 black. Along the upper labials a 

 white streak, edged with black. 



(2) 9-11 maxillary teeth. 



(o) Of the ma.xillary teeth the 

 third or the third and fourth much 

 enlarged. 



(4J 27ie last maxillary tooth en- 

 larged and grooved. 



(o) Rostral scarcely visible from 

 above. 



(6) Frontal twice to twice and a 

 half as long as broad. 



(7) Temporals 2+3 (rarely 

 2+2). 



(8) Snout short, profile truncate 

 or somewhat turned up in the 

 adult. (Head more distinct from 

 neck than in A. Lilljeboryi.) 



(9) Witb or without small 

 darker and lighter spots above. A 

 more or less distinct dark streak on 

 each side of the head, passing 

 through the eye. 



Assuming that Mr. Boulenger's description of P. pulveru- 

 lentus is correct, the difference between these two snakes, as 

 shown by the above comparison, is so great that it seems 

 strange that anybody should seriously think of uniting- 

 them. That Mr. Boulenger is, nevertiieless, inclined to 

 do so is unintelligible, all the more so because he has himself 

 put forth the dentition as well as the hypapophj'ses as distin- 

 guishing characteristics of very great value for the classifica- 

 tion of snakes, the snakes mentioned above differing widely 

 from each other in these two respects. As to the hypa- 

 pophyses, I have (' Annals,' Feb. 1905, p. 171) called atten- 

 tion to the fact that they are not of so much importance as 

 Mr. Boulenger is inclined to ascribe to them, which particularly 

 finds expression in his 'Catalogue of Snakes' concerning 

 Colubriuffi as well as Dipsadomorphinse, since he arranges the 

 genera of these tioo suhfamilies in two series^ " according to the 

 presence or absence of hypapophyses or hcemal processes on the 

 posterior dorsal vertebrce ^^ (Oat. iSnakes, i. p. 170 seqq., iii. 

 p. 27) ; and so I have of course not exclusively attaclied im- 

 portance to this difference, even if, as is quite natural, 1 have 



