KEVISTON OF THE KING SNAKES. 



245 



2. Elapsoides is a derivative of amaura, or of the form that repre- 

 sented it in the Texas region before the appearance of syspila and 

 triangulum. In the northeastern portion of its range it has given rise 

 to the color pattern variety, virginiana. 



3. The subspecies of triangulum may all be traced to a center of 

 dispersal in the plateau region of Mexico. 



4. The relationships of pyrrhomelaena and multicincta are doubtful, 

 but there seems to be the least difficulty in regarding fyrrliomelaena 



multicincta 



gentilis 



/" 



triangulum 



jn/rrhomelaena 



nelsoni 

 \ 



syspila 

 gentilis— ^amaura 



annulata 



mrgimana 



elapsoides 



ruihveni 



poly zona 



\ 

 micropholis 



Fig. 76.— a Diagrammatic Presentation of the Rel.*.tionships of the Forms of the Trungclum 



Group. 



as a specialized and isolated form, much older than the subspecies 

 of triangulum, and multicincta as the west coast representative of the 

 rest of the triangulum group. 



ISOLATED FORMS. 



LAMPROPELTIS MEXICANA (Garman). 



Fig. 77. 



1883. Ophibolus trinngulus, war. mexicanv^ Garman, S., Mem. Mus. Comp. Zool., 

 vol. 7, no. 3, p. 66 (type locality. Mexico, near San Luis Potosi; cotypoa, 

 probably numbers 4652 and 4653 of the collection of the Museum of 

 Comparative Zoology at Cambridge, Massachusetts). 



1902. Coronclla mericana GtJNTHER, Biol. Cent.-Amer., p. 110. 



No type was designated in the original description of mexicana, 

 and no specimens were listed. The description shows, however, 

 that there were at least two specimens, and it fits remarkably well 

 for two from that locality in the collection of the Museum of Com- 

 parative Zoology. The scales of both are in 23 rows; the ventral 

 plates are exactly 193 and 199, as in the origmal description; the 

 head is "much swollen at the temples;" and the pattern and colora- 

 tion answer well. According to the description, the caudals are 

 56-58 pairs, and the dorsal blotches are 38-40; these specimens 

 seem to have 55 pairs each of caudals, and about 39 blotches each. 

 These differences when compared with the coincidences are too 



