82 BULLETIN 199, UNITED STATES NATIONAL MUSEUM 



Genotype. — Holbrookia maculata Girard. 



Range. — Northern states of Mexico south to San Luis Potosf and 

 Durango. In the United States: Texas, New Mexico, and Arizona. 



Species. — Four, with twelve forms, of which ten are known to 

 occur or are to be expected in Mexico. 



KEY TO MEXICAN SPECIES OF HOLBROOKIA 



1. Tail flat, with broad, black, ventral bands; lateroventral black marks placed 



far posteriorly, continued dorsally above lateral fold, and slanting ante- 



roventrally on belly tezana (p. 85) 



Tail rounded; no ventral subcaudal marks save small spots in one subspecies; 

 lateroventral marks placed farther anteriorly, not extending upon dorsal 

 surface, and slanting posteroventrally on belly 2 



2. Several black spots under tail; dorsal pattern of large, well-defined spots 



equally sharp-edged on all sides; no light dots in pattern. 



maculata lacerata (p. 83) 

 No black spots under tail; pattern not as described 3 



3. Dorsal body scales distinctly keeled, rather small 11 



Dorsal body scales not keeled (although sometimes pointed and somewhat 



convex) , larger, flat 4 



4. Tail generally shorter than the snout-vent measurement, usually not over 



51 percent of total length (the higher proportions are of males) 5 



Tail generally as long as or longer than snout-vent measurement, 60-58 

 percent of total length (lower proportions are of females) 7 



5. Enlarged supraoculars in contact with frontals maculata elegans (p. 84) 



Enlarged supraoculars separated from frontals by a series of small scales. 6 



6. Size greater, maximum 71 mm., average 59 mm. snout to vent; in males a 



large blue patch surrounding lateroventral black spots on belly. 



raaculata dickersonae (p. 83) 



Maximum size 61 mm., average 50 mm. snout to vent; in males a smaller 



blue patch, or none, partially surrounding lateroventral black spots on 



belly maculata approximans (p. 83) 



7. Femoral pores usually less than 12 8 



Femoral pores usually 12 or more 10 



8. Upper labial region strongly flared, almost flat bunkeri (p. 84) 



Upper labial region less flared, obtuse 9 



9. Scales on limbs distinctly keeled; upper labials strongly imbricate. 



maculata pulchra (p. 84) 



Scales on limbs smooth; upper labials less strongly imbricate. 



maculata dickersonae (p. 83) 



10. Femoral pores about two-thirds as wide as pore scales are long in adult males, 



about one-half in adult females maculata elegans (p. 84) 



Femoral pores about one-half as wide as the pore scales are long, in adult 

 males, about one-fourth in adult females maculata thermophila (p. 84) 



11. Anterior gulars a transverse row of 4 subequal scales, the inner pair not 



separated by linear or rounded scales propinqua piperata (p. 85) 



Not so propinqua propinqua (p. 85) 



