413 



occasion I did not venture to separate a single specimen from Guaya- 

 quil, in the collection of the British Museum, and in a bad state of 

 preservation, from the common species (Catal. Col. Snakes, p. 153, 

 spec. «) ; but now, having found a very fine individual in Mr. Fraser's 

 collection, I can no longer doubt its specific difference. The most 

 striking character is the number of the upper labials, which in A. 

 liocercus is nine, the fourth and fifth coming into the orbit. It is 

 true that there occur scarce specimens of A. liocercus which have 

 one upper labial less, so far agreeing with A. occidentalis ; but the 

 relative length of the snout, nevertheless, remains the same. As the 

 snout and the head are considerably shorter in A. occidentalis, so 

 are the trunk and the tail ; it is altogether a stouter snake. Corre- 

 sponding to this, the scales are less elongate, especially those of the 

 outer rows, which are nearly rhombic. Further, the coloration is 

 nearly uniform, as in Philodryas viridissimus, the belly not being 

 white — merely of a lighter greenish than the back. The lips and the 

 chin, which are white in A. liocercus, are greenish ; and the black 

 streak through the eye in A. liocercus is here indicated only by a 

 blackish temporal streak. These differences together induce me to 

 separate the two species, which in the dentition agree with each other, 

 although the teeth of A. occidentalis appear to be rather stronger 

 and more widely set. 



The numbers of the plates are as follows : — 



Ventrals. Caudals. 



In A. liocercus from New Granada* 166 158 



In A. liocercus from Demerara 166 163 



In A. occidentalis from Guayaquil 172 133 



In A. occidentalis from Ecuador 160 130 



This similarity in the number of the ventral shields appears to 

 contradict my statement of A. occidentalis having a stouter trunk 

 than A. liocercus ; but there is a remarkable difference in the form 

 of those shields : their length is one-half only of their width in A. 

 liocercus, whilst it is nearly one-fourth in A. occidentalis. 

 Therefore the diagnosis of Ahcetulla liocercus will now be : — 

 Loreal shield none ; nine upper labials, the fifth and fourth coming 

 into the orbit (exceptionally, the second and third united) ; the 

 length of the snout is more than the distance between the eyes. 

 Scales in fifteen rows, those of the back keeled. Green above, white 

 beneath. A black streak through the eye ; the upper lip white. 



Berthold, I. c, describes Dendrophis liocercus from New Granada, 

 and it appears to me as if that specimen also ought to be referred to 

 A. occidentalis. He describes the body as slender, though rather 

 stout. " One would take it for a Herpetodryas, the body being at 

 least twice as thick as in D. liocercus ; the head also is much 

 broader. The colour is uniform leek-green ; belly and margins of the 

 ribs yellowish-green." 



13. Leptodeira (Dipsas) annulata, Schleg. 



* Berthold, Ueber Reptilien aus Neu Granada, p. 11. 



