6S4 On Aquatic Carnivorous Coleoptera or Dytiscidce. 



there is generally a minute fleck : the ventral segments are sometimes marked with 

 yellow. 



The sculpture on the elytra of the female consists sometimes of some very fine 

 short impressions extending along the middle of the elytra in the longitudinal 

 direction ; at other times the impressions are coarse and deep, occupying the 

 basal portion of the wing-case from the suture to near the outer margin. 



Very widely distributed in America, from Mexico and the West India Islands to Parana. 



Group 3. 



1071. Dytiscus basilaris, Harr., Acilhis basilaris, M.C. — Minor, parum convexus, 

 nitidus, subtus vel rufus vel piceus, supra niger, capite anterius et in medio verticis, 

 prothorace lateribus fasciaque mediali transversa, elytris lateribus fasciaque sub- 

 basali plus minusve integra, antennis pedibusque anterioribus testaceis ; colore 

 testaceo ad latera et ad apicem elytrorum a lineis et ab irrorationibus nigris disinte- 

 grate ; pedibus posterioribus piceis (vel rufis,) tibiis stepius nigricantibus ; epipleuris 

 angustis. Long. 10, lat. 5 1 m.m. 



Fern., prothorace elytrisque utrinque punctis elongatis, rudis profundis (plus 

 minusve numerosis) impressis. 



In the male of this species the large basal palette of the front tarsus is much larger 

 than the two next largest, these indeed are but little larger than the adjacent ones, 

 while the more outward ones are still smaller; the frinmnsr hairs are better 

 developed than in the allies, and are not Interrupted at the point of articulation 

 with the tibia as they are in all the other species. 



The species is very variable in size and colour, and in the sexual sculpture of the 

 female : but I do not find the characters constant in the series before me so that I 

 am unable to see more than one species in the variations : individuals reddish 

 beneath seem to occur only in California, and the magnitudes of the palettes in the 

 male seems to depart slightly from what exists in individuals from the eastern 

 United States ; I am not able from the series before me however to distinguish 

 more than one species, few of the individuals being in sufficiently good preservation 

 to allow me to form a positive opinion on such points. 



North America, United States and Mexico, Guatemala. 974. 



I. 71.— Genus CETHIONECTES. 

 Coxal lines distinct in their hinder portion, supra-articular border broad ; middle 

 femora with only short setae, 



A single species from tropical Africa. 



