I8 4 



AN INTRODUCTION TO ENTOMOLOGY. 



DD. Antennae 5-jointed.* 



E. Lateral margin of scutellum with a furrow in which the edge of 

 the wing-cover fits when closed. 

 F. Scutellum nearly flat, attenuated posteriorly. 

 G. Tibiae unarmed or furnished with very fine short spines. 



Fam. XXXIII. PENTATOMID^:. 

 GG. Tibiae armed with strong spines in rows. 



Fam. XXXIV.-CYDNiD^:. 

 FF. Scutellum very convex, covering nearly the whole abdomen. 



Fam. XXXV. CORIMEL^ENID^E. 



EE. Lateral margin of the scutellum without a furrow ; scutellum 

 very convex, covering nearly the whole abdomen. 



Fam. XXXVL SCUTELLERID^E. 



FIG. 150. Na- FIG. 151. An- FIG. 152. Cap- FIG. 153. Ffyr- FIG. 154. Lygce- FIG. 155. Co- 

 bidce. thocorince, sidce. rhocoridce. idte. reidce. 



Family XL 



( Water-boatmen^] 



To the Corisidce belong certain aquatic Hcteroptera which are 

 very widely and commonly distributed throughout our country. 

 They are of medium or small size, and of somewhat elongated oval 

 form. They occur in lakes, ponds, and streams, in both stagnant 

 and running water, and even in the salt lakes of Utah and Califor- 

 nia. 



All of the North American species of this family belong to the 

 genus Corisa. Fig. 156, which represents a 

 species of Corisa, illustrates the form of the 

 body. These insects may be distinguished by 

 the peculiar tarsi of the front legs. These 

 tarsi are flattened or scoop-like in form ; each 

 consists of a single segment, and bears a comb- 

 like fringe of bristles! The structure of the 

 head of these insects is quite unusual. In- 

 stead of being inserted in the prothorax, the 

 head overlaps that segment. The position of 

 the mouth-parts is also peculiar ; these are pushed through an open- 



* In certain families there are minute intermediate joints between the principal joints 

 of the antennae ; for the purposes of this table, these intermediate joints are not counted. 

 t Corlsidse, Corisa: coris (KoptS), a bug. 



FIG. 156. Corisa undulata. 



