REVISION OF THE KING SNAKES. 155 



LAMPROPELTIS TRIANGULUM NELSONI Blancltard. 



Fig. 65. 



1887. OpMbolus multistratus Cope, Bull. U. S. Nat. Mus. no. 32, p. 78 (Guana- 



juata). 

 1887. OpMbolus doliatus cocdneus (part) Cope, Bull. U. S. Nat. Mus., no. 32, p. 



78 (Guadelaxara; Colima). 

 1894. Caronella micropholis, var. A. Boulenger, Cat. Snakes Brit. Mus., vol. 2, 



p. 204. 

 1899. Lampropeltis micropholis oligozona Stejneger, N. Amer. Fauna, no. 14, 



p. 70 (Maria Madre Id). — Van Denburgh and Slevin, Proc. California 



Acad. Sci., ser. 4, vol. 4, 1914, p. 149. 

 1920. Lampropeltis triangulum nelsoni Blanchard, Occ. Pap., Mus. Zool., 



Univ. Mich., no. 81, p. 6, fig, 1 (type locality, Acambaro, Guanajuato, 



Mexico; type specimen, no. 46552, United States National Museum; 



E. W. Nelson, collector.) 



Description. — This is the west coast representative of the Mexican 

 Lampropeltes allied to triangulum. Its scutellation may be sum- 

 marized as follows: ventral plates, 199 to 231; caudals, 42 to 59; 

 supralabials 7, infrequently 8; infralabials 9, sometimes 10; pre- 

 oculars, 1, postoculars, 2; temporals usually 2 + 3 + 4; posterior chin 

 shields usually in contact, and general^ shorter than the anterior; 

 loreal longer than high, sometimes as high as long; scales rows on 

 middle of body 21 or 23, the commonest formulae being 21-23-21-19 

 and 21-19-17. 



The bodily proportions are practically the same as for the rest of 

 the group. The head is only slightly distinct from the neck, the 

 body cylindrical and of about the same diameter throughout, and 

 the tail tapers uniforml}^. The latter varies from 0.120 to 0.150 of 

 the total length (males, 0.128 to 0.150, average, 0.140; females, 0.120 

 to 0.137, average 0.129). The largest specimen examined was from 

 Maria Madre Island, and measured 1070 mm. 



The pattern of this form (fig. 65) like that of the other Mexican 

 members of the group, is made up of pairs of black annuli, 13 to 

 24 in number, bordering narrow rings of white or yellow and separated 

 by bands of red. It differs from polyzona chiefly in the fact that 

 the scales of the red areas are never tipped with black, and the pairs 

 of black rings average fewer in number. 



The black and yellow rings are complete on the belly, and this is 

 generally true of the red ones, also. Opposite the latter on the 

 belly, however, there is frequently a blackish mottling, and toward 

 the interior of Mexico, this space may be as completely filled with 

 black as in annulata. The yellow rings are of nearly uniform 

 diameter or may widen a little on the sides. They are sometimes 

 mottled with darker laterally, and a black spot may or may not be 

 present within their area on the belly. 

 186550— 21— Bull. 114 11 



