NATURAL SCIENCES OF PHILADELPHIA. 341 



rowed in front, and less strongly margined at the sides, and the upper snrface 

 of the body much more strongly punctulate ; the sides of the thorax also form 

 a very obtuse angle with the sides of the elytra. The sexual characters are 

 also different ; in the present, the claws of the anterior tarsi of the male are 

 long and slightly deformed ; in A. semivittatus they are not elongated, 

 but the inner one is toothed at the base. The trochanters and thighs of the 

 middle and hind legs are tinged with reddish brown. 



14. Agabus d i s c o r s, elongato-ovalis, minus convexus, reneo-niger, dense 

 minus subtiliter reticulatus, thorace lateribus modice rotundatis margine 

 L'rassiore rufescente, ad basin elytris vix conspicue angustiore, his longitudin- 

 aliter reticulato-strigosis, ore maculis que solitis verticalibus piceo-rufis, pedi- 

 bus rufo-tinctis. Long. *40. 



Mas nitidus, elytris thoracisque lateribus profundius strigosis, tarsis 

 anterioribus modice dilatatis, unguiculis anticis valde elongatis subsinuatis. 

 Femina opaca quasi velutina, elytris minus profunde strigosis. 

 Washington Territory ; Mr. Gibbs. A very distinct species. 



15. Helophorus alternatus, elongatus, capite rugoso, viridi-aeneo, 

 cupreo variegato, thorace latitudine fere sesqui breviore, postice subangus- 

 tato, lateribus late rotundatis margine depresso latiusculo testaceo, angulis 

 posticis subobtusis, prsecipue versus latera granulato viridi-aeneo, lineis 5 solitis 

 latis profundis aureis, intermediis sinuatis, elytris elongato-ovalibus thorace 

 parumlatioribus, testaceis, fusco-nebulosis, vel piceis testaceo-maculatis, striis 

 profunde crenatis, interstitiis seriatim punctulatis, 2ndo et 4to latioribus et 

 minus convexis subtus niger, antennis palpis pedibusque pallidis. Long. 

 14 -15. 



California ; Mr. Murray. This species is more elongated than H. 1 i n e- 

 a t u s, and is readily known by the elytra being somewhat wider than the 

 thorax, more regularly oval than usual, with 2d and 4th intervals wider and 

 less convex than the others. 



16. Hydrocharis glaucus, ovalis, convexus, supra nitore argenteo-cceruleo 

 glaucus, thorace lateribus magis rotundatis, basi recta angulis posticis obtusis 

 et rotundatis, punctis paucis versus latera notato, elytris striis e punctis 

 parvis compositis, interstitiis alternis irregulariter grosse punctatis, alter- 

 nis punctis paucis minutis impressis ; subtus niger, pedibus coeruleo-glaucis. 

 Long. -60. 



California ; Mr. A. Murray. A very beautiful species with the sides of the 

 thorax more rounded than in C. s ub s t r i a t us Zee, which it resembles 

 somewhat in the sculpture of the elytra, though the stria? of punctures are 

 more distinct, and the punctures of the intervals much larger. 



17. Philhydrus imbellis, ellipticus, convexus, nitidus, dense punctula- 

 tus, capite nigro-piceo, thorace piceo, lateribus pallidis, elytris piceo-ochraceis 

 vix conspicue striatim punctatis, stria suturali antice obliterata, subtus niger, 

 tibiis tarsisque testneeis. Long. - 24. 



One specimen ; California ; Mr. Murray. This species belongs to the group 

 (a, Lee. Proc. Acad. Nat. Sc. Phil. 7,369,) having the mesosternum and 

 presternum not carinated. It differs from the other species known to me by 

 the faint traces of striae upon the elytra; the three confused rows of punctures 

 seen in the others are here scarcely observed as separate from the rows of 

 punctures constituting the stria?. 



18. Philhydrus no rm atus, ovalis, modice convexus, nigro-piceus, niti- 

 dus, vix punctulatus, elytris striis integris 10, scutellarique e punctis digestis 

 compositis, antennarum basi palpisque testaceis. Long. -22. 



One specimen ; Bodega ; Mr. Davidson. The prosternum is not carinated, 

 the mesosternum has a small protuberance near its hind margin. The outer 

 1861.] 



