On Aquatic Carnivorous Coleoptera or Dytiscide. 269 
This group comprises,only two genera ; both have a very wide geographical 
distribution. 
Prosternal process very broad behind ; hind tibie very broad ;\ HYDROCANTHUS, 
size 4-7 m.m, of length. (vide p. 279.) 
Prosternal process moderately broad behind; hind tibie rather | CANTHYDRUS, 
slender ; size less than 4 m.m. of length. (vide below). 
I. 9.—Genus CANTHYDRUS. 
Prosternal process only moderately broad, not broader than long ; swimming 
leos rather slender. 
The numerous species* inhabit the warmer parts of the Old and New Worlds; 
they are but little understood as yet, and very similar to one another. 
30. Canthydrus sculpturatus, n. sp.—Ovalis, sat convexus, nitidus, ferrugineus, 
elytris abdomineque fuscis ; illis crebre profunde arguteque punctatis, punctis 
elongatis, versus apicem densioribus. Long. 25, lat. 13 m.m. 
The punctuation of the elytra makes this a very easily distinguished species. 
The only individual I have seen is a female, and has the apical ventral segment 
almost without impression. 
Brazil, (Santa Rita, August, 1850, Dr. Sahlberg). 515. 
31. Canthydrus vicinus, n. sp.—Ovalis, sat convexus, nitidus, ferrugineus, elytris 
sat crebre punctatis ; prosterni processu parce punctato. Long. 22, lat. 13 m.m. 
Extremely similar to Canthydrus sculpturatus but not so broad, and with 
prosternal process and coxal laminse more sparingly punctured. The two individuals 
before me are male and female. The male has a small indistinct oblong flattening 
or depression at the base of the apical ventral segment in the middle ; in the female 
there is a very obscure indication of carination along the middle of the hinder part 
of this segment. The male specimen has the elytra more closely and coarsely 
punctured than in the female, but I do not know whether this is sexual or merely 
an individual variation. 
Brazil, (Santa Rita, August, 1850, Sahlberg). 514. 
* Tn addition to those enumerated in the text, the following species should probably be placed in 
Canthydrus. Hydrocanthus auritus Rest. (No. 1,324 huj. op.); Manilla—Hydrocanthus lineatus, 
Wehncke (No. 1,326), near No. 49; Mexico.—Hydrocanthus rubripes, Boh. (No, 1,328), ? near No. 45 ; 
Uruguay.—Hydrocanthus testaceus, Boh. (No. 1,330), near No. 70; China.—Suphis puncticollis, Crotch, 
(No. 1,506), near No. 48; North America.—Suphis semipunctatus, Lec. (No. 1,507); North America.— 
Whether Hydrocanthus nanulus, Lec. (No. 1,327, North America) belong to the genus, is somewhat 
doubtful. 
2N2 
