676 On Aquatic Carnivorous Coleoptera or Dijtiscidce. 



greater or less distinctness of the pale band of the elytra : underneath the amount 

 of the yellow colour on the ventral segments shows a good deal of variation. 



North America, (Massachusetts, New York, Pennsylvania, Illinois). 959. 



1056. Acilius duvergeri, Gobert, Ann. Soc. Ent. Fr. (.5) IV, p. 441. — Haud latus, 

 subdepressus, testaceus, capite thoraceque signaturis transversis nigris, elytris 

 creberrime nigro-irroratis, pectore nigro ; thorace impunctato, parum nitido, elytris 

 subrugoso-punctatis, ad suturam versus basin fere Isevigatis ; corpore subtus minus 

 punctato, parum nitido. Long. 13, lat. Ik m.m. 



The male has on the undersurface of the very broad front feet three large palettes 

 differing little from one another in size, and outwardly a patch both in front and 

 behind of minute palettes borne on hairs, the fringing hairs are highly developed ; 

 on the middle feet the tarsi are not dilated, but the basal joint bears beneath 

 several small palettes; of the two females before me one has the sculpture of the 

 elytra the same as in the male, while in the other it is a good deal denser and more 

 rugose. 



Europe. Ihis species has only been found yet at Dax in the south-west of France. This excessively 

 limited distribution of a species is very remarkable. 960. 



1057. Dytiscus mediatus. Say, Acilius mediatus, M.C. — Haud latus, parum 

 convexus, nitidus, subtus niger, prosterno in medio testaceo, supra testaceus, capite 

 thoraceque nigro-signatis, elytris creberrime nigro-irroratis, fascia pone medium 

 maculisque apicalibus sat distinctis pallidis, pedibus anterioribus testaceis, poste- 

 rioribus nigris ; elytris crebre, versus basin parce subtiliter punctatis, punctisque 

 seriatis sat distinctis; coxis posterioribus parce, distincte punctatis. Long. Ill, 

 lat. 6^ m.m. 



The male has the front tarsi smaller than in Acilius semisulcatus ; beneath with 

 three palettes of moderate size and not differing much from one another, and out- 

 wardly with two patches of palette-bearing hairs, the fringing hairs but little 

 developed ; the intermediate tarsi are quite simple, without any peculiar clothing. 



I have seen very few specimens of this interesting species. According to the 

 individuals before me, there is probably a slight difference in the sculpture of the 

 thorax in the two sexes : in the male on this part there are very few punctures, 

 and they are so small as easily to escape attention, in the females they become a 

 little more distinct at some distance from each side. 



North America (Nebraska, Pennsylvania, Georgia, sec. Crotch). 961. 



