506 On Aquatic Carnivorous Coleoptera or Dytiscidce. 



692. Agabus punctatus Melsh., Proc. Ac. Phil. II, p. 27. — Ovalis, sat convexus 

 nitidu-s, rufescens, abrlomine pectoreque piceis, .supra senescens ; elytris sublpevigatis, 

 baud reticulatis, vix perspicue puiictulatis ; prothbrace sat magno. Long. 7^, 

 lat. ii m.in. 



The male has the three basal joints of the front and middle tarsi distinctly incras- 

 sate and furnished beneath with rather short hairs which bear small but distinct 

 palettes ; the claws of the front feet are shorter and more curved than in the female 

 and have a small obtuse tooth at the base ; the long apical spur of the hind tibia 

 is also thicker than in the female, and has its underside longitudinally striate. 



The species varies in the colour of the upper surface, which is sometimes more 

 rufescent, sometimes more seneous ; and the serial punctures of the elytra are in 

 some individuals coarser than in others. 



Nortli America. (Pennsylvania, Georgia, sec. Crotch). 77S. 



693. Agabus seruginosus, Aube, M.C. — Ovalis, sat convexus, nitidus, rufescens, 

 abdomine pectoreque piceis, supra subcenescens ; elytris subltevigatis, baud reticulatis, 

 subtilissime punctulatis; prothorace sat magno. Long. 7i, lat. 4^ ra.m. 



In the male the front and middle tarsi are almost without dilatation, and have only 

 a very small surface beneath clothed with hairs ; the claws of the front feet are short 

 and have a small swelling at the ba.so ; the interiacdiate femora bear a dense elon- 

 gate pubescence, and the intermediate tibiae a more scanty and short pubescence ; 

 the hind margin of the posterior femur forms a curve owing to the outer and 

 hinder angle being considerably produced and acute. 



This species I should have failed to distinguish from A. punctatus had it not been 

 for the remarkable male characters ; in nearly all particulars except the sexual 

 peculiarities the two species seem excessively similar ; Agabus feruginosus will 

 probably prove to be less convex, and more rufescent or less feneous above, and to 

 have the fine punctures on the elytra not quite so obsolete : the only good character 

 to distinguish tlie females will I think be found in a different arrangfement of the 

 punctures on the apical ventral segment. 



x^orth America. 779. 



Group 7. 



Hind coxae small, wings of metasternum large, hind tarsi feeble, but hind femora 

 with a distinct lamina at postero-external angle ; male front claws short and dentate 

 beneath ; no abdominal file ; prosternal process not, or only slightly, compressed, 

 glabrous or feebly punctate, either narrow or moderately broad ; cilire at angle of 

 lower surface of hind femur very rudimentary. 



Three species from both Old and New Worlds. 



