Vol. XXIX, pp. 93-94 June 6, 1916 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



A NEW TANTILLA FROM MEXICO. 

 BY THOMAS BARBOUR. 



When Stejneger described Tantilla vnlcoxi (Proc. U. S. Nat. 

 Mus., 25, 1902, p. 156) he closed his notice with the words: 

 "It would then be interesting to know what is Garman's T, 

 coronata from San Luis Potosi." The specimen mentioned by 

 Garman (Bull. Essex Inst., 19, 1887, p. 128) is now before 

 me, and I believe represents a new form, near T. vnlcoxi 

 Stejneger, and also close to T. bocourti Giinther, which unfortu- 

 nately I have not seen, and which was very inadequately de- 

 scribed. I imagine that this form may be an intermediate type, 

 perhaps annectant between these two species. I naturally have 

 submitted our specimen to Stejneger for comparison with the 

 type of T. wilcoxi, and he writes me as follows, under date of 

 March 28, 1916: 



"I have looked at your Tantilla and compared it with the type of 

 T. wilcoxi. The eye is smaller, thongh larger than in T, coronata. Top 

 of head very similar, though supraoculars smaller, corresponding to eyes, 

 head not so broad over temples. Color pattern practically identical. 

 But then your specimen is smaller than the type. However, your speci- 

 men has first pair of lower labials broadly in contact behind mental as 

 in T. bocourti, while in T. toilcoxi, they are separated by mental." 



Giinther, however, in describing T. bocourti (Biol. Cent., 

 Am., Kept., 1894, p. 149) begins by saying of his species: 

 "Vertical (= frontal) shield moderately broad, considerably 

 longer than broad, much broader than the supraocular." This 

 is not the condition in the example in hand, in which it is 

 more than moderately broad. Unfortunately Giinther makes 

 no mention whatever of the size of the eye. T. bocourti Giinther 

 was collected by the veteran Duges at Guanajuato. Pending 



21— Proc. Biol. Soc. Wash., Vol. XXIX, 1916. (93) 



