162 COLEOPTERA OF NORTH AMERICA. 



eyes, 9-jointed, the first and second joints thick, the last three 

 forming an oval club. 



Head deflexed; labruin distinct; mandibles small; eves 

 rounded, lenses large. 



Prothorax with the side pieces not distinct; presternum 

 not visible between the cox«; flanks excavated for the re- 

 ception of the antenna. 



Mesosternum short and wide, perpendicularly declivous 

 in front. 



Metasternum moderately large, side pieces very narrow. 



Elytra entire, descending widely on the flanks; epipleural 

 fold narrow, extending to the apex. 



Abdomen with five free ventral segments. 



Anterior coxae prominent, flattened at tip, forming two 

 small, subquadrate, contiguous plates, with a deep fissure 

 between them, in which is concealed the prosternum ; middle 

 coxa3 oval, distant; posterior transverse, not contiguous. 



Legs short, slender; tarsi filiform, -i-jointed, the first joint 

 longer than the following two; claws simple, small. 



Tliis family consists of but one genus, Georyssus; of it several 

 species are found in Europe and Asia, and two in the United 

 States ; one on each side of the continent. 



They are small, rounded, convex, roughly sculptured, black 

 insects, found at the margin of streams, on wet sand; they cover 

 themselves with a mass of mud, so that no part of the insect is 

 visible. 



Fam. XXXVII.— PARNIDAE. 



Mentum corneous, trapezoidal, or emarginate in front; 

 ligula large, not lobed. 



Maxillge exposed at the base, with two unarmed lobes. 



Antennae variable in form and position. 



Head usually retractile; labrum distinct; mandibles small; 

 eyes rounded. 



Prothorax with" the side pieces not separate; coxal cavities 

 widely open behind, completed by the mesosternum, variable 

 in form; prosternum prolonged behind the cox^e." 



Mesosternum sometimes excavated, sometimes emargi- 

 nate; side pieces attaining the coxaj. 



Metasternum with side pieces wide or narrow; epimera 

 (except in Psephenus) not visible. 



