450 COLEOPTERA. 



convex, roughly sculptured, black insects, found at the mar- 

 gins, of streams, on Avet sand ; they cover themselves with a 

 mass of mud, so that no part of the insect is visible. Georys- 

 sus ijasillus Lee. is our only species. 



Parnid^ MacLeay. These are aquatic beetles, having a 

 retractile head, and are often found clinging to submerged 

 stones, both in the larval and pupal states. Tlie body of 

 the beetle is "• clothed with a fine pu- 

 bescence, enabling a film of air to be 

 preserved beneath the water." The 

 larvse are hemispherical like a basin. 

 "■The larva of Psej)lienus Lecontei 

 Ilald. (Fig. 400, under side, enlarged 

 three times) is an elliptical object, 

 Fig. 400. with the margins widely extended be- 

 yond the bod^s and is seen on stones under the water of rapid 

 sti'eams ; it is especially abundant in the rapids of Niagara, 

 and differs in no important particular from the larwa of Heli- 

 chus of the next subfamily. It respires by branchial fila- 

 ments." (Leconte.) EJmis (Fig. 401, larva of a European 

 species) is known by the narrow, elongate scutellum. 



IIeterocerid^ MacLeay. "This family consists of but a 

 single genus, Heterocerus ; it is represented in every portion 

 of our territory. The species are numerous, but Aery similar 

 in form and color, so that care is necessary in distinguishing 

 them. They are oblong or subelongate, oval, densel}^ clothed 

 with short, silky pul)escence, very finely'- punctuate, and of a 

 brown color, Avith the elytra usually variegated with undulating 

 l)ands or spots of a yellow color. They live in galleries 

 which they excavate in sand or mud at the margin of bodies 

 of water, and, when disturbed, run from their galleries and take 

 flight, after the manner of certain species of Bembidium," 

 (Leconte.) 



LucAKiDyE Latrcille. This family is closely allied to the 

 next, and is often united with it, as it differs chiefly from 

 the outer lamellate joints of the autennse not being so closely 



