628 On Aquatic Carnivorous Coleoptera or Dytiscide. 
There is no perceptible difference of sculpture in the sexes of this species, either 
on the thorax or elytra. The male has the front tarsi moderately dilated and a 
little compressed, and furnished beneath with four rows of rather large, and closely 
placed, round palettes. 
The species is somewhat variable in form, size, colour, and sculpture. 
North America, (Massachusetts, Canada, Red River). 915. 
969. Colymbetes rugipennis, n. sp.—Ovalis, parum convexus, subtus niger, 
supra capite anterius rufo, posterius nigro rufo-bimaculato, prothorace testaceo, 
medio plaga nigro-fusca, elytris fuscis lateribus testaceis, pedibus rufis ; prothorace 
crebrius reticulato, lateribus versus angulos posteriores parum rotundatis ; elytris 
profunde transversim strigosis, strigis secundum sexum profundis. Long. 153, lat. 
7¢ m.m. 
The male differs very little in sculpture from Colymbetes sculptilis, but the female 
departs considerably in sculpture from the male, the reticulations of the thorax 
being very deep, and the transverse grooves on the elytra being considerably 
deeper on the basal half, while on the apical half they are hardly so deep or 
approximate as they are in Colymbetes sculptilis. The male tarsi are strongly 
dilated and very little compressed. 
Although closely allied to Colymbetes ccalpela this appears to me a distinct 
Species, it is smaller and less elongate, and less convex, the male tarsi are broader, 
less compressed, and the female is easily distinguished by its sculpture. 
North America. (Northern boundary of Nebraska, Sepr. 1874). 916. 
970. Colymbetes thomsoni, n, sp.—Ovalis, parum convexus, subtus niger, supra 
capite anterius rufo, posterius nigro, rufo-bimaculato, prothorace testaceo, medio 
plaga nigro-fusca, elytris fuscis lateribus testaceis, pedibus rufis ; prothorace haud 
profunde reticulato, elytris profunde transversim strigosis. Long. 15, lat. 74 m.m. 
The male has the front tarsi only moderately dilated and quite distinctly com- 
pressed ; in the female the reticulations of the thorax are deeper than in the male, 
and the strize on the basal portion of the elytra are deeper and less distant. 
Lapland, Iceland, (Greenland?). 917. 
971. Dytiscus dolabratus, Payk., Cymatopterus dolabratus, M.C.—Ovalis, 
parum convexus, subtus niger, segmentis ventralibus anguste rufo-fasciatis, ultimo 
dimidio parte rufo, supra capite anterius rufo, posterius nigro, rufo-bimaculato, 
prothorace testaceo medio plaga nigro-fusca, elytris fuscis lateribus testaceis ; pro- 
thorace crebrius reticulato, elytris profunde transversim strigosis. Long. 19, fat. 
7% M.m. 
