16 SYNOPSES ANH DESCRIPTIONS, 



Long, slender; 



Scales in 23 (21—23) rows, vent nils 260 ( + ) 



biscutatufn. 

 Scales in 21 rows, ventrals 206—210 ( + ) 



var. latifasciatum. 



Moderate; 



Postmaxillary tooth longer, grooved; 



Scales in 19—25 rows, ventrals 181—188 (+) 



armulatum. 

 dorsal series broad transverse bands 



var. septentrionale. 

 dorsal series of spots rather small 



torquatum. 

 Postmaxillary teeth in continuous series, not grooved; 

 Scales in 19 rows; ventrals 179 — 182 (+) 



discolor, 



SlBON BISCUTATUM. 

 Dipsas biscutata Than. Bibr., 1854, Erp. (Ha. VIT, 1153. 



Long, slender, compressed; bead distinct, broad oval, depressed, snout 

 prominent, broad, rounded; tail moderate, tapering. Eye large, pupil erect. 

 Mouth-cleft deep, slightly curved. Anterior maxillary teeth longer; pos- 

 terior large, isolated, grooved. Head-shields nine, broad. Rostral broader 

 than high. Nasal divided. Loreals two to four. Orbitals 2 to 3 — 2 to 3. 

 Temporals irregular. Labials 9 — 10, fourth and fifth usually under the 

 eye, the four preceding the last larger. Infralabials 11 — 13. Submentals 

 two pairs; posterior small, not in contact. Scales in 23 rows. Ventrals 

 264(+). Anal bifid. Subcaudals 94 ( + ) pairs. 



Light brown, punctulate, with broad transverse bands or rhombs of 

 brown, which are paler in the center and separated by spaces about equal 

 to their width. The bands become narrower toward the abdomen, at the 

 rd^c of which there is an alternating series of spots. Abdomen sprinkled 

 with brown; subcaudals with blotches. A light band across the head 

 behind the internasals; another across the frontal passes through the eyes 

 to the angle of the mouth. A V-shaped light spot on the vertex and a 

 light collar behind the occiput. (From D. & 13. and Jan.) Hab. Mexico 

 and southward, 



