1905.] AMPHIBIANS A.ND REPTILES. 223 



Pacific, terrestrial xerophile, and a more Atlantic and southern 

 rather hygrophile stock. The former is almost typically Sonoi-an, 

 except that it does not enter the plateau. Since Charhia shows 

 that it can endure a cold climate, the absence of similar forms on 

 the Mexican plateau may possibly date back to the ba]:'rier of 

 volcanic terrain, 



CoLUBRiD.E. — Of the bewildering number of these snakes in 

 Mexico only those have been selected for discussion which seem 

 to yield some tangible results, while such as are too widely 

 scattered or rather imperfectly known in their distribution have 

 been mostly left out. 



0. AGLYPH^, — Trojndonotus, decidedly a Nearctic genus, ex- 

 tending through the whole of Mexico, with greatly diminishing 

 numbers of species into Central, but not into South Ameiica or 

 into the Antilles. T. ordinafus (inch varieties) is the commonest 

 species in the Avhole of Mexico. T. vcdidu^ is a western form, 

 from Utah to Colima. T. sijyedjon s. fasciatus is eastern, from 

 east of the Rocky Mountains to Costa Rica. Others are confined 

 to the southern half of Mexico. 



Ischnognathus is Nearctic, extending over the plateau, re- 

 occiu'ring in Guatemala. 



Contia, clearly Nearctic, through Mexico, with preference for 

 the plateau and its western slope, into South America. 



Ficimia is Sonoran, scattered through Mexico. 



Zamenis. — Sonoran. Of the 9 American species, 8 occur in 

 Mexico, 3 of which are confined to the southern half or extend 

 into Central America, but not into the Antilles. Z. constrictor, 

 widely spread over the States, enters North Mexico. Z. ornatus, 

 seniilineatus, and tceniaius are typical of New Mexico, Arizona to 

 Sinaloa, continuing as Z, mentovarius as a western form from 

 Sinaloa, Colima, S. Oaxaca to Guatemala, Z. grahami is a 

 central and eastern foi'm from the Southern States right over the 

 plateau and the East to Tehuantepec. Z. indcherrhnus is southern, 

 from Salina Cruz to West Nicaragua ; lastly, Z. mexicanus has 

 been recorded from Colima, Central and South Guerrero, Guana- 

 juato, and from Cape Corrientes in Jalisco*. 



Coluber with Bpdotes and Pityophis are clearly Nearctic, with 

 some species in almost every State of Mexico ; none is Antillean, 

 although some extend far into South America. C. corals, the most 

 powerful Colubrine Snake of Mexico, inhabits the warm and hot 

 countries, with the wide range from the South-eastern States of 

 North America to Brazil. 



Coronella. — Nearctic. C. regcdis from Kansas, over the plateau 

 to Mexico City ; C. Icevis in Nuevo Leon ; C. annidata = 

 microjiholis from Texas to Para, in Mexico certainly all over the 



* Bocourt (Mission Scient. Mes.) states emphatically " au cap Corrientes sur le 

 Pacifique"; it is therefore rather perplexing that Giinther (Biol. Centrali-Americ.) 

 adds " Cuba, Mus. Paris," as a locality of this species. There happens to be a Cape 

 Corrientes at the western end of Cuba, 



