1 1 1*. ATRACTUS. 305 



one postoetilar (exeept ionally two); temporals 1+2; hix upper 

 labials, third and fourth entering the eye ; two pairs of chin-shield-;, 

 rior half as long as anterior. Scales in 17 rows. Ventrals 

 1 7- \ 7!> : anal entire ; .subcaudals i'4-^l'. t'niforra dark plumbeous 

 above, margins of scales lighter; a yellow occipital bar ma}' be 

 present, ems-ing the parietal shields; vcntrals white, mottled with 

 leaden, or uniform leaden. 



Total length 455 millim. ; tail 45. 



Mexico (San Luis Potosi and Hidalgo). 



6. Atractus longiceps. 

 Rhabdosoma longiceps, Cope, Proc. U.S. Nat. Mus. ix. 1886, p. 189. 



Agrees in most respects with _1. litifi-ontalis^ but snout more 

 elongate and pnrfrontals much longer than broad. Ventrals 1~;>; 

 subcaudals 28. Extremity of tail with a compressed horny cap. 

 Colour everywhere blackish ; some brownish shades on the sides 

 near the head : free edges of ventral and subcaudal shields, and of 

 lateral scales, lighter. 



Total length 445 millim. ; tail 44. 



Vera Cruz, Mexico. 



7. Atractus peruvianus. 



Rabdosoma peruviunum, Jan, Arch. Zool. Anat. Phys. ii. 1862, p. 12, 

 and Icon. Gen. 10, pi. iv. fig. 2 (1865). 



Snout obtuse. Rostral much broader than deep, just visible from 

 above ; internasals small ; pneirontals not quite as long as broad ; 

 frontal small, as long as broad, as long as the praefrontals, much 

 shorter than the parierals ; loreal at least twice as long as deep; 

 two postoculars : temporals 1+2; six upper labials, third and 

 fourth entering the eye ; four lower labials in contact with the 

 single pair of chin-shields, which are moderately large and separated 

 from the symphysial. Scales in 17 rows. Ventrals 140 ; anal 

 entire ; subcaudals 31. Urown above, with five longitudinal series 

 of black spots; ventrals black, with a white spot at the outer end; 

 lower surface of tail white, spotted with black. 



Total length 280 millim. ; tail 4(. 



Tern. 



8. Atractus guentheri. 



RhftbdoKHM niaciilatum, part.. (Hinth. Cut. p. :M1 (1868). 

 (J.-ojihis ^u.-ntlu-ri, ll'iii-/irrir, /'/<. /<>l. Soc. 18G1, p. 115, pi. xix. 



lig. 1 : (innth. /<><>/. AVr. ]s - .>, p. 151. 

 K.-ilnio-oma uiiivittiittnii, Jun, Arrti. Zool. Anat. Phys. ii. 1802, 



p. 15, ,/ J,.,,,,. <;<. 11, pi. ii. ii-. -2 ' 



Snout rounded. Rostral small, broader than deep, just visible 

 from above; interna>als very small ; prafrontals broader than long 

 trontal a little broader than long (or as long as broad), as long ai 



VOL. n. x 



