On Aquatic Carnivorous Coleoptera or Dytiscidije. 599' 



I. 57.— Genus AGABETES. 



Prothorax without lateral margin; upper surface with a dense remarkable 

 sculpture. Coxal lines conspicuous, parallel in front, gently divergent behind, and 

 marking off a large, broad, coxal border. 



The only species known is found in North America, but is apparently very rare. 



906. Colymbetes acuductus, Harr., Agahiis acuductus, M.C. — Ovahs, latus, sub- 

 depressus, subopacus vel opacus, rafescen.s, pectorc, abdomine, prothorace elytrisque 

 infuscatis, thorace elytrisque versus latera rufescentibus; supra striolis disjunctis, 

 brevibus, sat profundis crebre ornatus; prothorace brevi, sine margine laterali, 

 angulis posterioribus rotundatis. Long. 71, lat. 4^ m.m. 



The male has the basal joints of the front and middle tarsi much incrassate and 

 greatly compressed, and furnished beneath with scanty, long hairs, mixed with 

 which are other rather short hairs bearing rather large palettes ; the claws of the 

 anterior feet are very elongate, and little curved ; they are also rather thick, the 

 front one being somewhat more thickened than the other, but it becomes slender 

 near the extremity so as to cause the outline beneath to appear sinuate: the apical 

 ventral segment is traversed along the middle for its whole length, with two very 

 remarkable perfectly parallel deep grooves. There is also a sexual disparity in the 

 sculpture of the upper surface, the female being more dull than the male, and 

 having the short impressions on the elytra more densely packed. 



In this species the obliteration of the subserial punctures of the elytra is com- 

 plete. 



North America, (Pennsylvania, Canad;)). 820. 



I. b^.—GQiiUHMATUS. 



Prosternum sulcate along the middle. 



Three species are known, two of them Australian, the other North American. 



907.. Colymbetes bicarinatus. Say, Matus bicnrinatus, M.C. — Oblongo-ovalis, 

 minus convexus, nitidus,- ferruginous, fere unicoloratus, elytris vix obscurioribus, 

 corpore supra parce subtiliter punctulato ; capite minus brevi ; thorace ad latera 

 marginato, prope marginem Fate, subobsolcte, longitudinaliter impresso ; prosterno 



