162 Journal New York Entomological Society. t'^'o^- ^^• 



Described from specimens received from Prof. H. F. Wickham, 

 Iowa City, Iowa. Collected at Kalispel, Montana. Prof. E. T. 

 Cresson, Jr., has kindly compared my specimens with the type. 



Type. — In the museum of the Philadelphia Academy of Sciences, 

 Philadelphia, Pa. 



Habitat. — California and Montana. 



HALIPLUS Latreille. 



Haliplns Latreille, Hist. Nat. Ins., Ill, 1802, p. yj. 

 Cneniidotiis Illiger non Erichson. Illiger Mag., 1802, p. 373. 

 Hoplitus Clairville, Ent. Helv., II, p. 218. 



Type. — Dytiscus ruficollis DeGeer. Memoires Ins., 1774, p. 404. 



Terminal segment of the palpi subulate, shorter than the preced- 

 ing; palpi with but few sensory pits. Submentum trilobed, the med- 

 ian lobe strongly emarginate. Pronotum truncate, strongly narrowed 

 in front, convex above, widest at the base. Elytra with the rows of 

 punctures regularly arranged; intervals with fairly regularly arranged 

 smaller punctures. The posterior coxse conceals the first three seg- 

 ments of the abdomen. Hind tarsi as long as or longer than the 

 tibiae; first tarsal joint longer than the fourth; claws small. 



This genus contains by far the largest number of species, in all 

 over one hundred, widely distributed. They live in pools, stagnant 

 water, etc., and are abundant usually where there is a supply of fila- 

 mentous algae growing. The habits of the adults, their life-histories, 

 etc., will be fully discussed in the second part of this paper. 



Key to the Species of Haliplus. 



A. Pronotum with paired basal impressions (striolse). 



B. Prosternum deeply grooved ; elytral spots distinct, prominent ; basal 



impressions less than one third the length of pronotum. 



ruficollis DeGeer. 



BB. Prosternum not deeply grooved ; elytral spots usually indistinct, 



small, or sometimes entirely wanting; basal impressions more than 



one third the length of the pronotum longiilits Leconte. 



AA. Pronotum without paired basal impressions. 



C. Prosternum not margined, flat or slightly convex or concave laterally. 



D. Species entirely rufous, punctures on elytra, especially at base, 



being slightly dark vanconverensis, n. sp. 



DD. Species not entirely rufous, yellowish in color with black mark- 

 ings always present. 



