.^lO'H 



On Aquatic Carnivorouf! Coleoptcra or Di/dscidu; 



The seven genera may be readily distinguished as follows : — 



Coxal incision distinct ; upper sur- | 

 face with sculpture. American. J 



Coxal incision wantiui; ; upper sur- (^ 

 face without sculptui-e. Asiatic, j 



Coxal border 

 verv broad. 



Upper surface with sculpture ; 

 thorax without lateral margin ; 

 prosternum not sulcate. 



Prosternum lonffitudinally sulcate 

 alon" the middle. 



^4 



f Coxal lines veiy closi; to one another : \ 



I prosternum but little incrassate I- 



^ , . , along the middle. I 



Coxal border I 



very narrow. ' ri i r n i- 4. *. ^ 



Coxiil lines normally distant ; pro- | 



sternum much incrassate along the }■ 



middle. J 



I'Vont border of hind coxa but little arched, wing of metasternum rather 

 large, not linear, not deflexed outside coxa. 



AGYLMDUS. 



( Vide p. 596.) 



LAC'coyEcrrs. 



(Tic/Bp. ."598.) 



AGA BETES 



(r,W?p. 599.) 



MAT US. 

 (Vide p. 599.) 



COI'ELATUS. 

 ( Vide below.) 



COPTOTOMUS. 

 (CiWep. GOl.) 



LANCETES. 

 ( Vide p. 6U2.) 



I. 54.— Genus COPELATUS. 



Coxal lines extremely close to one another, especially in their hinder portions, 

 where just before their abrupt divergence to form the borders of the coxal processes 

 they are very nearly contiguous with the central line forming the suture of the two 

 00X03 ; at the anterior part of the coxal processes they become excessively hue so 

 that they can with difficulty be perceived, and are abruptly diverted outwards at 

 right angles to tlieir former course. 



The species ary numerous"'' and are found in nearly all the warmer parts of the 

 world ; the sculpture of the elytra which frequently consists of elongate striae offers 

 a ready method of arranging them in fourteen groups ; seven of these groups 

 possess in addition to the conspicuous regular stria), a short additional stria placed 



* In addition to those enumerated in the succeeding text, it is prolmble that the following should be 

 referred to the genu.s. Colymbetes bimaculatus, Perrond (No. 1216)?group I; New Caledonia. — Copelatus 

 angustatus, Chev. (No. 1258) near No. 882; Cuba. — Copelatus australiw, Clark, (No. 1259) near No. 

 815; Australia. — Copelatus basalis. Boh. (No. 1260); Caffraria. — Copelatus elongatulus, Macl. (No. 

 1261) near No. 808 ; Australia. — Copelatus externus, Kiisch, No. 1262); Peru. — Copelatus forniosus, 

 WoU. (No. 1263); Africa aid Cape Verde Islands. — Copelatus gallapagoensis, Wat. (No. 1264) near 

 No. 875 ; Galapagos Islands. — Copelatus normalis, Er. (No. 1265) : Peru. — Copelatus obtusus, Boh. (No. 

 1266); Caffraria. -Copelatus quadrisignatns, Regt. (No. 1167); Manilla. — Copelatus striatellus, Boh. 

 (No. 1268^1 Cartiaria. — Cojielatus striaticollis, Luc. (No. 1260); Si iu(h America. — Copelatus substriatus, 

 Kirsch, (No. 1270); Peru. — Copelatus undecimstriatus, Aubc, (No. 1271); Cayeune.—Dytiscus bicolor, 

 Fab. (No. 1286) ; Africa. 



