On Aquatic Carnworous Coleoptera or Dytiscide. 615 
937. Rhantus anisonychus, Crotch, Tr. Am. Ent. Soc. IV, p. 409.—Ovalis, fere 
elongatus, sat convexus, sat nitidus, subtus niger, supra testaceus, vertice nigro- 
variegato, prothorace in disco maculis duabus coalescentibus nigris, elytris 
creberrime nigro-irroratis, antennis testaceis, extrorsum parum infuscatis, pedibus 
piceo-testaceis : prothorace margine laterali sat discreto ; tarsis posterioribus sat 
gracilibus, unguiculo interno quam externo duplo longiore; metasterni laciniis 
extrorsum brevibus. Long. 113, lat. 6 m.m. 
The male has the front and middle tarsi a gcod deal incrassate, and moderately 
compressed, with the under surface bearing large palettes, and the marginal hairs 
largely developed and curled at their terminations ; the front claws are excessively 
elongate, appearing when viewed from the front quite slender, the anterior one is 
much longer than the other and is slightly bisinuate beneath ; the middle claws are 
thick, the outer being much longer than the more curved inner one: the female 
has the lateral portion of the wing cases from the shoulder to the middle, and also 
the lateral portion of the thorax, with the reticulate sculpture much deeper. 
North America, (California). 885. 
938. Rhantus discedens, n. sp.—Ovalis, fere elongatus, sat convexus, subtus 
piceo-rufus, capite in medio prosternoque rufis, supra testaceus, capite nigro, anterius 
rufo, prothorace plaga transversa discoidali nigra, elytris creberrime nigro-irroratis, 
antennis pedibusque rufis, illis extrorsum leviter fuscescentibus ; prothorace lateribus 
curvatis, margine laterali sat discreto; tarsis posterioribus subrobustis, articulo 
quarto vix lobato-producto, unguiculo interno quam externo plus duplo longiore : 
metasterni laciniis brevibus. Long. 113, lat. 6 m.m. 
I have seen but a single female of this, which is no doubt a very distinct species ; 
this individual has the basal portion of the elytra covered with deep coarse im- 
pressions, rendering the surface very rugose, the apical half of the wing cases 
bearing the usual fine reticulations ; the thorax has on each side a large patch of 
coarse sculpture. 
North America, (Cailfornia). 886. 
939. Colymbetes atricolcr, Aubé, M.C.—Ovalis, niger, nitidus, vertice testaceo- 
bimaculato, antennis rufis, pedibus piceis; supra crebrius punctato-reticulatus, 
subtus leevigatus, nitidus, neque strigosulus nec punctatus ; prothoracis margine 
laterali subobsoleto; tarsis posterioribus robustis, articulis haud lobato-productis, 
unguiculo externo elongato, quam interno haud duplo breviore. Long. 14, lat. 
72 m.m. 
The male has the basal joints of the front and middle tarsi a little incrassate, and 
greatly compressed, and clothed beneath with rather long hairs and four rows of 
