898 



COLmRIDJt. 



111. DIROSEMA. 



Maxillary short, with 10 to 16 teeth, tho anterior and posterior 

 of which are tho shortest ; mandibular teeth small, decreasing in 

 length posteriorly. Head distinct from neck ; eye small, with 

 vert ically elliptic pupil ; proeocular absent, loreal and pnuf rental 

 entering the eye. Body moderately elongate, cylindrical; scales 

 without pits, smooth or foebly keeled, in 15 or 17 rows ; ventrals 

 rounded. Tail short ; subcaudals in two rows. 



Central America. 



Connects Tropidodipsas with Geophis. 



Synopsis of the Species. 



I. Scales in 17 rows. 



Nostril between two nasals ; fifth upper 



labial largest ; scales smooth 1. tricolor, p. 298. 



Nostril between two nasals ; sixth upper 



labial largest; scales faintly keeled . . 2. omiltemanum, p. 299. 

 Nasal undivided; sixth upper labial 



largest ; scales keeled 3. psephotum, p. 299. 



II. Scales in 15 rows 4. brachycepTialum, 



[p. 299. 



1. Dirosema bicolor. (PLATE XIV. fig. 2.) 



Geophis bicolor, Gilnth. Ann. $ Mag. N. H. (4) i. 1868, p. 416, 



and Biol. C.-Am., Kept. p. 91 (1893). 

 Rhabdosoma guttulatum, Cope, Proc. Amer. Philos. Soc. xxii. 1885, 



p. 385. 



Snout broad, rounded. Rostral a little broader than deep, visible 

 from above ; internasals much broader than long, two fifths to one 

 half tho length of the praefrontals ; frontal as long as broad or a 

 little broader than long, as long as its distance from the end of the 

 snout ; nostril between two rather large nasals ; loreal twice as long 

 as deep ; two postoculars (rarely one) ; temporals 1 + 2 or 1 + 1 + 2; 

 six upper labials, third and fourth entering the eye, fifth largest and 

 usually in contact with the parietal ; two pairs of chin-shields, 

 anterior longest and in contact with three or four lower labials. 

 Scales smooth, in 17 rows. Ventrals 151-168 ; anal entire ; sub- 

 caudals 38-50. Black above, with a more or less distinct lateral 

 series of whitish dots ; the scales of the two or three outer series 

 white in the centre ; upper lip white ; lower parts white, uniform 

 or spotted with black. 



Total length 425 millim. ; tail 95. 



Mexico. 



a-d. rf (V. 159, 151 ; C. 47, City of Mexico. Mr. Doorman [C.]. 



50) & $ (V. 167, 168; (Types.) 



C. 38,41). 



-/. <7- c? (V. 149; C. 46) La Cumbre de los Arra- Dr. A. C. Buller 



& $ (V. 163, 161 ; C. 42, etrados, Jalisco, 8500 [C.]. 



46). ft. 



