On Aquatic Carnworous Coleoptera or Dytiscide. 677 
I. 70.—Genus THERMONECTES. 
Coxal lines distinct in their hinder portion ; supra-articular border broad ; elytra 
not punctate (except for a sexual sculpture in certain females), Middle femora 
with elongate sete. 
The species* may be arranged in three artificial groups : 
1. Elytra (at any rate on the basal portion) yellow with numerous black specks, 
after the manner of Rhantus. Nos. 1058 to 1064. 
2. Elytra black, with definite yellow markings forming conspicuous spots or 
fascize, but no minute speckles. Nos. 1065 to 1070. 
3. Elytra black, with irregular marginal yellow marks which are of a longitudinal 
character and more or less divided by black lines and specks. No. 1071. 
Group l. 
1058, Acilius nigrofasciatus, Aubé, M.C.—Robustus, nitidus, levigatus, elytris 
punctis seriatis sat conspicuis, subtus rufo-testaceus, supra testaceus, vertice 
thoraceque transversim nigro-signatis, elytris nigro-irroratis, pone medium fascia 
lata transversa, integra, perconspicua nigra. Long. 113, lat. 7 m.m. 
Mas, levigatus, nitidus. 
Fem., elytris ad basin prothoraceque utrinque punctis elongatis, rudis impressis. 
In the male the three larger palettes on the underside of the front feet, are of 
about one size. 
This species is extremely closely allied to the following, but is perhaps 
really distinct, it is rather larger and comparatively broader in front, and has the 
black fascia on the wing-cases excessively broad and conspicuous, and with no trace 
of any interruption; these are all the points I can find to distinguish the 
male, but the female is very easily distinguished by its more conspicuous sexual 
sculpture ; the elytra bear on their basal half coarse and deep short impressions or 
elongate punctures, they extend all across the base of the wing-case from the 
scutellum to the shoulder, and are also quite conspicuous on each side of the 
thorax. 
I have seen but few specimens of this species ; the thoracic black marking is no 
doubt variable, generally it consists of two transverse black lines, more or less 
united at their outward termination, and separated from one another by about the 
* The descriptions mentioned in the following list also refer to this genus. Acilius cinctatus, Aubé 
(No. 1172 huj. op.), near No. 1070 ; Mexico.— Acilius laporti, Aubé (No. 1174) near No. 1059; Brazil. 
—Acilius laticinctus, Lec. (No. 1175) near No. 1071; California.—Acilius maculatus, Aubé (No. 1176) 
near No. 1059 ; Mexico.—Thermonectes intermedius, Crotch. (No. 1508)? No. 1071 var.; California. 
48S 2 
