On Aquatie Carnworous Coleoptera or Dytiscide. 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 epipleure. 
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 Aubé and subsequent authors. 
Tam 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 Aubé quoted Fabricius. It will be desirable therefore, it appears to me, to 
cite Aubé as the authority for the name of the species, and to add to the synonyms 
“? Dytiscus immarginatus, Fab. Ent. Syst. App. p. 444.” 
Tropical Africa, (Senegal, Gambia), Caffraria, (Madagascar 1). 1006. 
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 male of this species the front tarsi are only moderately developed, 
attaining about 24m.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 epipleuree 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. Soe. Fr. V, VII, p. clvi.—Robustus, ovalis, 
sat latus, convexus, supra olivaceus, subtus niger, pedibus anterioribus et intermediis 
femoribus basi apiceque tibiisque anterioribus szepius dilutioribus, pedibus 
posterioribus nigris; antennis rufis; elytrorum epipleuris versus apicem sat latis, 
planatis. Long. 35, lat. 192 m.m. 
5 A2 
