On AquatL Carnivorous Coleoplcra or DytiscidcB. 445 



521. Hydroporus solitariiis, n. sp. — Ovalis, dense brevissime subtilissimeque 

 pubescens fere opacus, rufo-testaceus, elytris fuscis, signaturis testaceis ; protborace 

 raargine baud tenui ; elytris deuse subtilissime punctatis, stria suturali obsoleta ; 

 coxis posterioribiis dense fere subtiliter punctatis. Long. 4, lat. 2s m.m. 



Tbe only individual I bave seen is a male, and bas tbe front and middle tarsi 

 ratber strongly dilated. 



North America, (Massachusetts). 285. 



Group 3. 

 Tbe numerous species of tbis group may be tabulated as follows : — 



A. (Species 522 to 527.) Middle coxpe ratber widely separated, (in tbe first three 



species tbe base of the thorax is but little produced over the elytra, in tbe 

 second three it is conspicuously so produced). New World species only. 



B. (Species 528.) Coarsely punctured and yet distinctly shining benei.th ; no 



thoracic impression, middle coxa3 very closely approximate. 



C. (Species 529 to 533.) Thorax with a short lateral impression, upper surface 



but little convex ; under surface dull, but as it were smooth, bttle punctate. 



D. (Species 534 to 536.) Thorax with an abbreviated lateral stria; body dull 



beneath, being finely coriaceous, and with a coarse punctuation more or 

 less developed ; form convex : outline of thorax and elytra continuous. 



E. (Species 537 to 540.) No thoracic impression; beneath coniewhat coarsely 



punctured, but still distinctly shining : outline of thorax and elytra very 

 discontinuous. 

 1 F. (Species 541 to 548.) Thoracic stria more or less abbreviated in front and 

 behind; body shining beneath, size quite small, (about 2 m.m. long). 

 G. (Species 549 to 551.) Thoracic stria entire and very distinct ; form depressed, 

 surface shining beneath. 



A. 



522. Hydroporus eximius, Motsch., M.C. — Ovalis, latiusculus, opacus, nigricans, 

 supra testaceus, capite rufescente, protborace anterius et posterius elytrisque 

 signaturis nigris ; elytris fere impunctatis, seriebus suturali et discoidali punctorum 

 impressis, hac minus distincta, versus suturam subdepressis ; cor])ore subtus opaco, 

 impunctato, ruguloso ; prosterni processu lato, medio fortiter carinato, apice 

 acummato. Long. 41, lat. 2f m.m. 



Tbis species is more elongate and less rotund than Hydroporus addendus, and 

 with tbe base of tbe thorax narrower than tbe elytra. 



I bave seen only a single specimen. The species is allied to H. mexicanus (No. 

 527), but is readily distinguished by its colour and the sub-carinate disc of tbe elytra. 



California. 224. 



3 JI 2 



