AMERICAN PHILOSOPHICAL SOCIETY. 509 



COLYMBETES Clairville. 

 Antenna longer than the head, setaceous ; scutel distinct ; 

 basal joints of the four anterior tarsi of the male almost equally 

 dilated, not patelliform; palpi filiform, 



1. C. eryt[h]ropterus.— Black; elytra dark-reddish-brown , 

 margin and base paler ; feet towards the tips piceous ; body 

 rounded behind. 



Length not quite two-fifths of an inch. 



Dytiscus eryt[h'\ropterus Melsh. Catal. 



Body black, above divided by minute lines into minute, irre- 

 gular, longitudinal, or suborbicular spaces ; head black, two in- 

 distinct piceous spots on the vertex, and an abbreviated line and 

 puncture on the front each side ; antenna and palpi rufous ; tho- 

 rax black, dorsal line abbreviated, obsolete, lateral edge arquated ; 

 scutel black, plain ; elytra reddish-brown, darker on the posterior 

 disk, immaculate, exterior margin and base paler, rounded be- 

 hind, inflected margin black ; pectus and postpectus black ; ster- 

 num acutely carinated ; feet piceous, middle of the thighs black, 

 nails of the anterior pair in one sex dilated in the middle and 

 compressed ; venter black, segments piceous at tip. 



Rather less convex than the succeeding species, and some- 

 what more dilated. The color of the head and thorax is mani- 

 festly distinct from that of the elytra, and forms a good specific 

 character. 



[Belongs to Agdbus. — Lec] 



2. C. FENESTRALis. — Black, slightly bronzed ; elytra four- 

 spotted, anterior spots obsolete, terminal ones distinct, beneath 

 piceous-black. 



Length two-fifths of an inch. [9^3 



Dytiscus fenestralis Melsh. Catal. 



Body black, above slightly bronzed and divided into very 

 minute suborbicular, depressed granules, beneath piceous-black ; 

 head with two obsolete piceous spots on the vertex, a definite, 

 impressed, abbreviated, oblique, frontal line, with a smaller 

 oblique one above, each side ; antennae and palpi piceous ; thorax, 

 an obsolete, punctiform, central line, often wanting ; elytra, on 

 each a submarginal, elongated, obsolete, rufous spot behind the 

 1823.] 



