CHECKLIST OF THE SNAKES OF MEXICO 109 



Cosmiosophis Jan, Arch. Zool. Anat. Fis., vol 2, 1863, p. 289 (type, Liophis tri- 

 cinctus Jan). 



GenoUjfe. — PUocercus elapoides Cope. 



Range.— So\\i\\&vi\ Tamaulipas and the Isthmus of Tehuantepec 

 southward on both coasts into South America. 



Species. — About 13 or 14 species and subspecies, of which 8 occur 

 in Mexico.^^ 



KEY TO MEXICAN FORMS OF PLIOCERCUS 



1. Rings on body alternating red and black, all subequal in length (black 



rings a little the longer) 2 



Yellow rings, as well as red and black, present on body; black rings or 

 saddles in triads, or, if single, the spaces between them at least a half 

 greater than their own length 3 



2. Black rings numerous, on body 25 to 27, on tail about 17 ; primary caudal 



black rings separated from each other by spaces equal to their own 

 length; in addition, secondary, incomplete black rings (saddles) present 



in middle of red spaces on tail ■ aequalis 



Black rings less numerous, 14 on body ; black tail rings twice as long as 

 interspaces, which lack secondary black rings or saddles bicolor 



3. Black rings very long, covering 6 to 10 ventrals and 8 to 11 dorsals— andrewsi 

 Black rings short, covering 2 to 5 scale length elapoides 4 



4. Black rings single on body or, if triad, the outer rings considerably nar- 



rower than the yellow rings 5 



Black rings triad on body and tail, the outer rings of each triad very dis- 

 tinct and as long as or longer than yellow rings; primary black rings 

 complete (except nuchal), on body 9 to 10 in males, 9 to 15 in females; 

 primary black rings on tail 5 to 8; infralabials usually 9, some- 

 times 8, rarely 10; ventrals 128 to 131 in males, 133 to 144 in 

 females elapoides elapoides 



5. Most primary rings on body incomplete ventrally, 9 to 16; infra- 



labials usually 10; ventrals 124 to 128 in males, 127 to 130 in 



females elapoides laticollaris 



All primary black rings, except nuchal collar, complete 6 



6. Black rings on body 11 to 13 in males, 13 to 18 in females ; black rings on 



tail 8 to 12; usually 9 infralabials; ventrals 127 to 128 in males, 128 



to 134 in females 7 



Black rings on body 5 to 10, on tail 4 to 6 ; usually 10 infralabials ; ven- 

 trals 123 to 128 in males, 132 to 137 in females elapoides diastemus 



7. Snout uniformly black, except at lip; nuchal black collar not involving 



labials or parietals and covering eight scale lengths on nape; primary 

 black rings longer, involving three or four ventrals and four or five 



dorsal scale lengths elapoides celatus 



Snout mottled ; nuchal black collar involving tips of parietals and poste- 

 rior supralabials, and covering five scale lengths on nape ; primary black 



»= A record of Urotheca elapoides (Boulenger, Catalogue of the snakes in the British 

 Mivseum, p. 183) for "Jalisco" cannot be allocated with any known form of the genus and 

 probably represcntpi an iiniiaiiied form. B()ulen.:er's record for Atoyac doc cit.). (Ji'eirrro, 

 ■would seem to refer to the town by the same name in the state of Veracruz, and therefore 

 pertain to P. e. elapoides. 



584960—45 8 



