On Aquatis Carnivorous Coleoptera or Dytiscide, 445 
521. Hydroporus solitarius, n. sp.—Ovalis, dense brevissime subtilissimeque 
pubescens fere opacus, rufo-testaceus, elytris fuscis, signaturis testaceis ; prothorace 
margine haud tenui; elytris dense subtilissime punctatis, stria suturali obsoleta ; 
coxis posterioribus dense fere subtiliter punctatis. Long. 4, lat. 25 m.m. 
The only individual I have seen is a male, and has the front and middle tarsi 
rather strongly dilated. 
North America, (Massachusetts). 285. 
Group 8. 
The numerous species of this group may be tabulated as follows :— 
A. (Species 522 to 527.) Middle coxee rather widely separated, (in the first three 
species the base of the thorax is but little produced over the elytra, in the 
second three it is conspicuously so produced). New World species only. 
B, (Species 528,) Coarsely punctured and yet distinctly shining benexth ; no 
thoracic impression, middle coxee 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, little 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. 
>) 
. (Species 537 to 540.) No thoracic impression; beneath somewhat coarsely 
punctured, but still distinctly shining: outline of thorax and elytra very 
discontinuous. | 
i 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, prothorace anterius et posterius elytrisque 
signaturis nigvis ; elytris fere impunctatis, seriebus suturali et discoidali punctorum 
impressis, hac minus distincta, versus suturam subdepressis ; corpore subtus opaco, 
impunctato, ruguloso; prosterni processu lato, medio fortiter carinato, apice 
acuminato. Long. 4%, lat. 24 m.m. 
This species is more elongate and less rotund than Hydroporus addendus, and 
with the base of the thorax narrower than the elytra. 
I have 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 the elytra. 
California. 224. 
3 M2 
