On Aquatic Carnivorous Coleoptera or DytiscidcB. 367 



BVom Sitka I have seen a small variety, (Hydroporus erythrostomus, Mann.), in 

 which the elytra are largely pale with a few fuscous vittse, this form is narrow and 

 the punctuation fine, and the colour beneath is dark. 



In California there is a variety, (H. obscurellus, Lee.) which is very dull, and of 

 an obscure fuscous red colour, almost without markings on the elytra, and the 

 colour of the under surface dark. 



In Nevada occurs a variety in which the elytra are much variegate, and the 

 colour beneath is between black and yellow. 



In Utah the specimens I have seen are large, with much variegate elytra, and 

 black beneath. 



H. macularis, Lee. is entirely pale beneath, it is of small size, and I can see 

 nothing to distinguish it from the Sitka specimens except the rather paler colour of 

 the under surface. 



In Central America the colour is dark, and the punctuation of the elytra scanty. 



The specimens from Chili are variable in colour and punctuation, but I cannot 

 find any constant distinction from the North American specimens : and the same 

 remark applies to H. bonariensis, Steinheil. 



H. strobeli, Steinl. from S. Luis, differs but little from the North American 

 type. 



North and South America, from Sitka to Buenos Ayres. 102, 115, 129, 130, 132, 135. 



319. Hydroporus lacustris, Say, M.C — Oblongo-ovalis, nitidulus, parce subtiliter 

 pubescens, testaceus, abdomine pectoreque nigris ; elytris ochraceis, sat crebre sub- 

 tiliter punctatis ; coxis posterioribus nitidis, impunctatis. Long. 1|, lat. 1 m.m. 



The punctuation of the upper surface in this species is finer than in any of the 

 North American immediate allies. The colour of the under surface varies, some- 

 times the ventral segments are black, sometimes yellow. The tarsi are slender in 

 all the specimens I have examined, (eight in number), and I see no sexual 

 characters. 



The species is easily distinguished from Hydroporus affinis, and H. fuscatus, by 

 the stria at the base of the elytra being rather longer than the thoracic stria ; it 

 has also traces of a sutural stria on the elytra. 



North America, (Massachusetts, Texas). 133. 



320. Hydroporus fuscatus. Crotch, Tr. Am. Ent. Soc. IV, p. 391. — Oblongo- 

 ovalis, minus angustus, nitidulus fere sine pubescentia, rufescens, elytris fusco- 

 signatis, sat crebre fortiter punctatis, striga basali brevissima vel omnino nulla ; 

 coxis posterioribus medio sparsim fortiter punctatis. Long. 2, lat. 1 m.m. 



This species is readily distinguished from all the varieties of Hydroporus affinis, 

 (No. 318), by the comparatively coarse punctuation of the hind coxse, and the very 



