628 On Aquatic Carnivorous Coleoptera or Dytiscidce. 



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. 



Nortl) America, (Massachusetts, Canada, Red River). 915. 



9(>9. Colymbetes ruj^ipennis, n. sp. — Ovalis, parum convexus, subtus niger, 

 su^ira capite anterius rufo, posterius nigro rufo-bimaculato, prothorace testaceo, 

 medio plaga nigro-fusca, elytris fuscis lateribus testaceis, pedibus rufis ; prothorace 

 crebrius reticulate, lateribus versus angulos posteriores parum rotundatis ; elytris 

 profunda transversim strigosi.s, strigis secundum sexum profundis. Long. 15|, lat. 

 7l 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 sculptilis, 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. 



Nortli America. (Nortlieni lioundary of Nebraska, Sepr. IST-i). 91G. 



970. Colymbetes thomsoni, n. sp. — Ovalis, parum convexus, subtus niger, supra 

 capite anterius rufo, posterius nigro, rufo-bimaculato, prothorace testaceo, medio 

 plaga nigro-fu.sca, elytris fuscis lateribus testaceis, pedibus rufis ; prothorace hand 

 profunde reticulato, elytris profunde transversim strigosis. Long. 15, lat. *7h m.m. 



The male has the front tarsi only moderately dilated and quite distinctly com- 

 pressed ; in the female the reticulations of the thoi'ax are deeper than in the male, 

 and the striae on the basal portion of the elytra are deeper and less distant. 



Lapland, Iceland, (Greenland/). 917. 



971. Dytiscus dolabratus, Payk., Cymatoj^terus 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. Iti, iat. 

 7f m.m. 



