266 



FAMILY VI. HYDBOPHILID.E. 



elytra usually striate; mesosternum elevated between and in front 

 of the middle coxa 1 . About 25 species are known from the United 

 States, many of them being common to this country and Europe. 

 Of these Dr. Horn states that "but a small number owe their pres- 

 ence in our fauna to introduction by human agency. They appear 

 to be rather members of a circumpolar fauna, equally native in 



either hemisphere, and dis- 

 tributed at a time when con- 

 tinental division was less ab- 



r u p 1 than at present. ' ' 



B b Eleven species have been 



Fig- 130. Rg. 131. taken in Indiana and several 



A, middle coxal cavity. B, metasternal area. (After Horn.) ,1 i i j_i 



others doubtless occur. 



KEY TO INDIANA SPECIES OF CERCYON. 



a. Intervals of elytra alternately higher or subcostiform at apex, the stria3 

 deep ; surface sparsely pubescent : color pale reddish-brown. 



518. PUBESCENS. 

 aa. Intervals flat or slightly convex; surface smooth. 



l>. Metasternal area extended on each side by an oblique line. (Fig. 



130.) 

 c. Thorax without basal marginal line, its surface wholly black. 



d. Elytra piceous, with pale apex; surface distinctly punctulate; 



palpi and antennae piceous. 519. BLEMORRHOIDALIS. 



dd. Elytra reddish, with a large scutellar triangle and humeral stripe 



piceous. 

 e. Elytra very distinctly punctulate ; epipleura piceous ; palpi pale. 



520. MELANOCEPHALUS. 



ee. Elytra indistinctly punctulate ; epipleura pale ; last joint of 



palpi piceous. 521. PYGM.EUS. 



cc. Thorax with distinct basal marginal line, paler at sides; elytra 



pale with transverse piceous band behind the middle; palpi pale. 



522. NIGRICEPS. 

 66. Metasterual area median only. (Fig. 131.) 



f. Side marginal lines of thorax extending for a short distance along 

 the basal margin ; elytra dull reddish-yellow with a large oval 

 piceous spot on suture behind middle which extends narrowly to 



ff. Side marginal lines reaching the hind angles only. 



//. Interval between the seventh and eighth striae normally wide, 



with at least two rows of punctures. 

 //. Form oval, never very convex; head oblique. 



/. Elytra piceous black, with a sharply limited yellowish apical 

 space extending along the sides toward the base. 



523. PR.ETEXTATUS. 



