THE SNAKE GENUS TRIMORPHODON — SMITH 161 



Diagnosis. — A member of the upsilon group, having a transverse, 

 light nuchal collar; dorsal bands few (13 in type), little narrower on 

 sides than on middorsal line, and much longer ventrally than light 

 spaces between; ventrals 219, caudals 76, scale rows 23, in type; no 

 interocular light bar. 



Description of holotype. — Supralabials 8 or 9, fourth and fifth 

 entering orbit on one side, third also on other ; two large loreals and 

 on one side a third small loreal at posterolateral border of second 

 loreal ; preoculars 2 or 3, upper somewhat the largest and in contact 

 with frontal ; three postoculars, median somewhat the smallest ; three 

 anterior temporals, followed by three secondary temporals on one side, 

 four on other; 12 infralabials, six in contact with chin shields, five 

 with anterior pair; posterior chin shields separated medially, nar- 

 rower and shorter than, and about two-thirds the size of anterior 

 chin shields. 



Scales in 21-23-15 rows, smooth, with paired apical pits; scales 

 above anus slightly convex; ventrals 219; caudals 76; anal divided. 



Maxilla with 10 teeth, in four groups; three anterior teeth, the 

 anterior smallest of the three and subequal in size to ungrooved teeth 

 in other groups, the posterior somewhat larger than second, which is 

 very nearly as large as posterior grooved teeth; one tooth in second 

 group, about size of first tooth, separated from other teeth on either 

 side by a short but very evident diastema ; four teeth follow, smallest 

 of the maxilla, very slightly decreasing in size; two posterior teeth 

 enlarged, offset, separated by a distinct diastema (subequal in length 

 to other diastemata) from preceding teeth. 



Hemit^enis long (25 caudals), slender (not everted) ; proximal tliird 

 with numerous ridges capped by very minute, scarcely discernible 

 spines; adjacent sixth with about 50 small spines, which extend to 

 the middle of the hemipenis ; distal half without spines, ridged, with 

 three large flounces, which have tiny papillae on their free edges ; distal 

 half with tiny papillae ; tip with somewhat larger papillae, apparently 

 not bifurcate; sulcus single. 



Top of head dark, with numerous tiny light flecks, no trace of reg- 

 ular markings except a median, V-shaped mark posteriorly, apex for- 

 ward; sides of head more light than dark, top of head more dark 

 than light; nuchal collar white, with some dark stippling, its pos- 

 terior border nearly straight, somewhat concave, a little more than 

 two scale lengths behind parietals medially ; anterior border of nuchal 

 collar vague, grading into darker color of head, especially laterally. 

 Thirteen very broad, dark cross bands on body, four on tail; first 

 five bands covering 19 to 21 scale lengths medially, remaining bands 

 decreasing in length posteriorly; first five bands covering 15 to 18 

 scale lengths on first scale row, remaining bands fewer, but all bands 



