180 BULLETIN 187, UNITED STATES NATIONAL MUSEUM 



Bands on body paired, each half \Yell defined and usually separated 

 medially from its mate; middle preocular considerably larger than 

 lower, broadly in contact with border of orbit ; scale rows usually 19 

 in front of anus dunni 



7. Subcaudals single 8 



Subcaudals double atrox asper 



8. Scales in 23 rows or more 9 



Scales in 21 rows or less ; size smaller 10 



9. Nasal in contact with rostral, not over two, and as few as no scales 



whatever, bordering nasorostral contact above or below ; lower bor- 

 der of postocular stripe usually involving only posterior temporal 



of lower row mexicanus 



Nasal separated from rostral by a row of three small scales ; lower bor- 

 der of postocular stripe involving two to four posterior temporals of 

 lower row nummifer 



10. Width of a supraocular about half distance between supraoculars; sub- 



caudals 22 to 34 ; brown ; terrestrial 11 



Width of a supraocular one-third distance between supraoculars, or 

 less ; subcaudals 44 to 67 ; green ; arboreal 12 



11. Scale in 21 rows; upper preocular large, forming part of canthal ridge; 



loreal small, excluded from canthal ridge, not in contact with supra- 

 ocular godmani 



Scales in 19 or 17 rows ; upper preocular small, excluded from canthal 

 ridge; loreal large, forming part of canthal ridge, in contact with 

 supraocular barbouri 



12. Head scales smooth ; scales in 19 rows nigroviridis aurif er 



Head scales keeled; scales in 21 rows bicolor 



BOTHROPS ATROX ASPER (Gannan) »» 



Bothrops atrox Dum^kil, Bibron, and Dum£ril, Erpetologie generale, vol. 7, 

 pt. 2, 1854, pp. 1507-1509.— DiTMAES, Snakes of the world, 1931, pis. 60, 64. 



Bothrops atrox dims Jan, Elenco sistematico degli Ofidi, 1863, p. 126 (type 

 locality, "Buenos Ayres; Mexico; Orizaba"; cotypes in Torino, Giessen, 

 Leiden Mus. ; restricted to specimen from Buenos Aires) (part). 



Trimeresurus atrox Mooquakd, Mission scientifique au Mexique et dans rAm6- 

 rique centrale, Kept., livr. 17, 1909, pp. 940-941. 



Trigonocephaliis asper Garman, Bull. Mus. Comp. Zool., vol. 8, 1883, p. 124. 



Type.—MviS. Comp. Zool. No. 2718, 2 heads. 



Type locality. — Obispo, Panama. 



Range. — From Tamaulipas and extreme southeastern San Luis Po- 

 tosi on the Atlantic coast, and from the Isthmus of Tehuantepec on 

 the Pacific, southward along both coasts into South America, including 

 Yucatan (known in Mexico from the states of Campeche, Chiapas, 

 Oaxaca, San Luis Potosi, Tabasco, Veracruz, and Yucatan; a record 

 from Tamaulipas (Martin del Campo, Foil. Div. Cient. Univ. Nac. 

 Mex., No. 27, 1937, p. 14) seems to be based upon probability of oc- 

 currence instead of actual specimens [as are several other state rec- 

 ords in the same paper] and the Atoyac, Guerrero, record of Boulenger 

 (Catalogue of the snakes in the British Museum, vol. 3, 1896, pp. 



** We use this name at the suggestion of Dr. Dunn. 



