0)1 Aquatic Carnivorous Colcoptera or Dytiscidce. 679 



In the male, the most basal of the three largtir palettes on the underside of the 

 front feet is considerably larger than the other two. 



The black marks on the thorax are less extensive than in the allied species, the 

 anterior one is placed a little behind the front margin, and is not interrupted in 

 the middle even when most diminished, and is never connected with the posterior 

 marks, which consist of two very closely placed lines joined at their extremities 

 so as to enclose a yellow transverse line which is most frequently divided in 

 the middle ; when the black marks take a greater extension than usual, this 

 enclosed yellow line may be entirely absent. The sjiecies varies much in size, and 

 somewhat in the relative amounts of the black and yellow colours ; and in the 

 smallest females the sexual sculpture is nearly entirely absent ; the punctures on 

 the thorax ajjpear however to be not quite so variable as the more conspicuous 

 sculpture on the elytra. 



South America, Mexico, (Bahia, Petropolis, Para, Peru.) 964. 



1061. Dytiscus circumscriptus, Latr., Acilius circumscriiJtus, Jl.C. — Convexius- 

 culus, parum latus, Itevigatus, nitidus, subtus niger, prosteruo ex parte majore 

 testaceo, supra testaceus, vertice nigro-signato, thorace anterius et posterius in medio 

 nigro, elytris nigro-irroratis, irrorationibus post medium in fasciam transversam 

 nigram condensatis, et post fasciam irregularibus, antennis pedibusque anterioribus 

 testaceis, pedibus posterioribus extus nigris, femoribus externe late rufescentibus ; 

 elytrorum epipleuris angustis. Long. Hi, lat. 6| m.m. 



Fern., elytris in medio longitudinis j)unctis elongatis subtilibus impressis, pro- 

 thorace versus latera punctis impressis minus subtilibus. 



In the male the tliree larger palettes of the undersurface of the front tarsi are 

 of about one size, and not very large. The fine impressed linear punctures on the 

 wing-cases of the female form a broad patch extending from the base about two- 

 thirds of the length of the elytra. 



In this species the transverse black mark on the thorax always attains respec- 

 tively the front and hind margins, and so leaves yellow across the middle only a 

 short stripe between them. 



The species varies a good deal in size, and in the greater or less condensation of 

 the black spots of the upper surface, occasionally the sides of the hind body are 

 obscurely spotted with yellow. The sculpture of the female is evidently variable, 

 for there exists in Dejean's collection an individual of that sex, which shows no 

 trace of the impressions on the elytra, and very little of the thoracic punctuation. 



Widely distributed in the New World, from Mexico aud the Antilles to Monte Video. 965. 



1062. Thermonectes depictus, (Reiche), n. sp. — Convexiusculus, latiusculus, 

 laevigatas, nitidus, subtus piceus, prosterno anterius rufescente, supra testaceus, 



