AMERICAN PHILOSOPHICAL SOCIETY. 515 



1. H. UNDULATUs. — Ferruginous ; elytra trifasciate with black. 

 Length about three-twentieths of an inch. 



Dytiscus iindulatus Melsh. Catal. 



Body ferruginous, very numerous, minute, villous punctures, 

 hairs adpressed to the surface ; head destitute of large, indented, 

 frontal punctures ; antennas and palpi paler ; thorax at base and 

 tip black, lateral edge very slightly arquated ; elytra, suture and 

 three undulated irregular bands black, of the latter, one is basal, 

 one central, and the other subterminal. 



The bands sometimes occur dilated and decurrent, so as to 

 forma common black disk to the elytra. 



[Also described subsequently as II. fasciatus Harris ; the % is 

 II. puhipennis, and the 9 H. velutinus Aube. — Leg.] 



2. H. OPPOSITUS. — Blackish; head and base of the thorax 

 ferruginous ; elytra with six whitish marginal spots or subfascia. 



Length rather less than three-twentieths of an inch. 



Body with very numerous, villous, minute punctures, hairs 

 adpressed to the surface ; head rufous . or ferruginous, four or 

 six indented, frontal, distant punctures ; thorax ferruginous, 

 black at tip, about three indented punctures, placed transversely ; 

 elytra black, each with an irregular humeral spot, another placed 

 upon the margin behind the middle, and a third apical one yel- 

 lowish, edge yellowish ; postpectus and venter blackish or deep 

 piceous ; pectus and feet yellowish-testaceous. 



This was sent to me as a distinct species by Dr. J. F. Mel- 

 sheimer. It is very like undulatus. 



[This seems to be the species afterwards described as //. jiroxi- 

 raus Aubc. — Leg.] 



3. H. NIGER. — Black, villous, obscure, immaculate ; head and 

 lateral margins of the thorax and elytra obscure rufous. [103] 



Length more than three-twentieths of an inch. 



Dytiscus niger Melsh. Catal. 



Body black, obscure, very numerous, minute, villous punctures, 

 hairs adpressed to the surface ; head obscure rufous, paler be- 

 neath, dusky each side of the front, a slightly indented spot 

 each side before instead of the impressed line and punctures ; 

 antennae dusky towards the tip of each of the terminal joints ; 

 palpi, terminal joints blackish ; thorax black, very obscure rufous 

 1823.] 



