On Aquatic Carnivorous Coleoptera or Dijtiscida. 725 



size of C owas, but the males of the two species may always be very easily 

 distinguished by the difference in the tarsi, and the females by the want of 

 sculpture and the simple epipleurse. 



Dytiscus immarginatus, Fab. — This name first appeared in Ent. Syst. App. p. 

 444, (1794), that in the Syst. El., quoted in Munich Catalogue, being several years 

 subsequent. The description appears to me to point to Cybister binotatus, rather 

 than to this species, to which it has been assigned by Aube and subsequent authors. 

 I am not aware that any Fabrician authentic example exists to settle this point ; 

 and in Dejean's collection the name of immarginatus was assigned to the species for 

 which Aube quoted Fabricius. It will be desirable therefore, it appears to me, to 

 cite Aub^ as the authority for the name of the species, and to add to the synonyms 

 "? Dytiscus immarginatus. Fab. Ent. Syst. App. p. 444." 



TroiJical Africa, (Senegal, Gambia), Caffraria, (Madagascar ]). lOOG. 



1137. Cybister modestus, n. sp. — Ovalis, sat latus, parum convexus, supra 

 olivaceus, prothoracis lateribus vage ferrugineis, subtus nigro-piceus, pedibus 

 anterioribus et intermediis piceis, rufo-variis, pedibus posterioribus nigricantibus, 

 antennis rufis ; elytrorum epipleuris versus apicem sat latis, planatis. Long. 33, 

 lat. 18 m.m. 



In the mole of this species the front tarsi are only moderately developed, 

 attaining about 2\ m.m. in the transverse direction, and are very similar to those 

 of C. immarginatus, as are also the intermediate feet. The female too is quite 

 without sexual sculpture. 



The species is closely allied both to C. immarginatus and C. operosus ; it differs 

 from C. immarginatus by its less convex form and smaller size, and by the fact that 

 the epipleuras in their posterior portion are distinctly a little broader and flatter ; 

 from C. operosus it differs by a more elongate and less convex form, by its showing 

 on the upper surface less tendency towards explanation of the sides of the elytra 

 near their posterior part, by the male front tarsi being rather larger, and the 

 sexual hairs of the middle feet shorter, and by the entire absence of any rudiment 

 of a supplementary claw on the female hind tarsus. 



West Africa, (Cameroons, Isubu, Gaboon.) 1067. 



1138. Cybister distinctus, Regt., Ann. Soc. Fr. V, VII, p. clvii. — Robustus, ovalis, 

 sat latus, convexus, supra olivaceus, subtus niger, pedibus anterioribus et intermediis 

 femoribus basi apiceque tibiisque anterioribus ssepius dilutioribus, pedibus 

 posterioribus nigris ; antennis rufis ; elytrorum epipleuris versus apicem sat latis, 

 planatis. Long. 35, lat. 192 m.m. 



5 A 2 



