380 



KANSAS UNIVERSITY SCIENCE BULLETIN. 



Natrix rhombifera Hallowell. 



Holbrook's Water Snake. 



Tropidonotus rhomhifer Hallowell, Proc. Acad. Nat. Sci. Phila., 1852 

 p. 177. 



Ntrodia holbrookii Baird and Girard, Cat. N. Amer. Rept., Ft. I, Serp., 

 1853, p. 43. 



Tropidonotus fasciatus (var.) rhomhifer Boulenger, Cat. Snakes Brit. Mu8., 

 I, 1893, p. 244. 



Fig. 12. 

 Natrix rhombifera Hal. 



Dorsal scales in twenty-seven rows ; first row faintly keeled, 

 all of the others strongly keeled. Scales not notched. Frontal 

 long, narrow, flaring anteriorly. Superciliaries narrow ante- 

 riorly, broader posteriorly, Occipitals large, outer margins 

 irregular. Internasals small, wedge-shaped. Nasals large, 

 Nares small, situated between the nasal plates, Loreal sub- 

 triangular. Oculars 1-3 or 1-4, Supralabials eight, fourth 

 entering the orbit ; sixth and seventh largest. Infralabials 

 eleven (occ. twelve), sixth largest, Gastrosteges 140-150. 

 Urosteges 55-75. Anal divided. Urosteges in two series. 



Color above drab gray, below greenish yellow. Three rows 

 of transverse black spots above ; about thirty-five to anus ; 

 twenty on tail. Lateral spots alternating with dorsal. Dorsal 

 spots seven scales wide by two long ; lateral spots covering the 

 same number of scales and extending to the inferior row. 

 Black markings on the base of the scales connect the lateral 

 spots with the dorsal. Gastrosteges with large, triangular 

 black spots near the ends ; two or three small spots between 

 the larger spots on each gastrostege. The triangular spots on 

 the urosteges are very large. Upper part of head lead color. 

 Superior labials lighter, bordered with brown or black. Under 

 part of head and neck yellowish white. 



