118 C0LE0PTERA OF NORTH AMERICA. 



Maxillae exposed at the base, which is elongated; lobes two, 

 coriaceous, not armed, but sparsely ciliate ; palpi 4-jointed, 

 short. 



Antennae inserted at the internal margin of the eyes, but 

 in front, short, 11-jointed, joints 5 — 11 forming an oblong 

 serrate club. 



Head large; eyes rounded, finely granulated; front promi- 

 nent; labrum large, rounded, ciliate over its whole surface; 

 mandibles stout, prominent, fringed internally with a ciliate 

 membrane, and furnished externally with a strong carina. 



Prothorax transverse, with rounded angles, side pieces not 

 separate; prosternum lobed in front, acute behind; anterior 

 coxal cavities widely open behind. 



Mesosternum very short, deeply emarginate; side pieces 

 small, diagonally divided. 



Metasternum moderate, meeting the first ventral segment; 

 side pieces wide. 



Elytra entirely covering the abdomen. 



Abdomen composed of five nearly equal ventral segments, 

 the fifth only being movable, the others connate; the first 

 marked each side with an elevated curved line reaching the 

 posterior margin * 



Coxas, anterior oval, transverse, with a distinct trochantin ; 

 middle ones rounded, angulated externally, separated by the 

 anterior part of the metasternum ; hind ones transverse, 

 nearly contiguous. 



Legs stout; tibias dilated, armed with rows of spines, and 

 fitted for digging; tarsi 4-jointed, second and third joints 

 shorter than the others, not lobed beneath, but fringed with 

 long hairs ; claws simple. 



This family consists of but a single genus, Heterocerus ; it is 

 represented in every portion of our territory. The species are 

 numerous, but are very similar in form and color, so that care 

 is necessary in distinguishing them. They are oblong or sub- 

 elongate, oval, densely clothed with short silky pubescence, very 

 finely punctuate, and of a brown color, with the elytra usually 

 variegated with undulated bands 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. 



* This elevated line is finely striate transversely, and is a stridulating 

 organ ; the hind legs, by friction against it, produce a quite distinct sound. 



