614 On Aquatic Carnmwvorous Coleoptera or Dytiscida. 
The male characters seem to be the same as those of Colymbetes divisus (No. 
930); in the female the reticulation on the sides of the elytra near the middle is 
deeper, and in some individuals there is also a development of patches of this 
deeper reticulation along the lines of indistinct serial punctures. 
North America, (Hermit Lake). 882. 
935. Colymbetes binotatus, Harris, Rhantus binotatus, M.C.—Ovalis, robustus, 
sat convexus, subopacus, subtus niger, prosterno ru‘o abdominis lateribus rufo- 
variegatis, supra testaceo vertice nigro-variegato, prothorace medio maculis duabus 
nigris, elytris creberrime nigro-irroratis, antennis pedibusque testaceis, illis extror- 
suin leviter infuscatis ; prothorace margine laterali tenui anterius obsoleto ; elytris 
ereberrime subtilissimeque reticulatis; pedibus posterioribus crassis, unguiculo 
interno quam externo duplo longiore. Long. 11, lat. 6 m.m. 
The male has the front and middle tarsi a good deal incrassate, and rather 
strongly compressed, and furnished beneath with four rows of rather large palettes, 
the claws of the front feet are rather short, and are bisinuate beneath, the anterior 
being rather the longer ; on the middle feet the outer claw is a good deal longer 
than the abruptly curved inner one. 
Though this species much resembles the shorter and more robust forms of kh. 
plebeius, it is abundantly distinct, and besides the characters mentioned above has 
the side wings of the metasternum shorter. It varies a good deal in size and form, 
and alittle in sculpture. The females from the United States have the reticulation 
on the middle and front part of the outer portion of the elytra coarse, but in the 
specimens from Mexico I find only slight traces of this coarser sculpture. 
Mexico, Guatemala, Western United States, (Peru ?). 883. 
936. Colymbetes mexicanus, Cast., Rhantus meaxicanus, M.C.—Ovalis, robustus, 
sat convexus, subopacus, subtus niger, prosterno rufo, abdominis lateribus rufo- 
variegatis, capite thoraceque rufis, illo vertice nigro-variegato, hoc maculis duabus 
parvis nigris, elytris nigricantibus, margine Jaterali apiceque testaceis, hoc nigro- 
irrorato, antennis pedibusque rufis, illis extrorsum leviter infuscatis ; prothorace 
margine laterali tenui anterius obsoleto ; elytris omnium densissime subtilissime- 
que reticulatis ; pedibus posterioribus crassis, unguiculo interno quam externo vix 
duplo longiore. Long. 11, lat. 6 m.m. 
This species is very closely allied to the preceding one, but has the elytra black, 
and their sculpture still denser and finer. The male characters seem to be nearly 
the same. I find no difference in the sculpture of the females. 
Mexico ; Guatemala. 884. 
