On Aquatic Carnivorous Coleoptera or Dytiscide. 513 
one species. Gaurodytes coriaceus, Sahl., (Not. Fenn. XIV, p. 174) is also I think 
a variety of the female of this species. 
This appears to be an arctic, alpine, and subalpine species. 
Europe, Siberia, Greenland, North America, (Sweden, Finland, Lapland, Britain, Germany, France, 
Northern Italy ; Labrador, Hudson’s Bay, White Mountains). 744. 
707. Agabus borealis, (dissimilis, Sahl.), n. sp.—Oblongo-ovalis, haud convexus, 
subnitidus, niger, supra fusco-zeneus, elytris versus latera pallidioribus, antennis 
pedibusque rufis, illis fusco-maculatis, prothorace margine laterali tenuiore ; elytris 
sat nitidis (¢), vel fere opacis (?). Long 64, lat. 34 m.m. 
This is probably another variety of Dytiscus congener, with which I have not 
however united it, as the males have the surface of the elytra rendered a little 
silky by an excessively fine and indistinct sculpture. The male tarsi, and the 
other structural characters show no difference from D. congener. 
Arctic Siberia, (found by Dr. Sahlberg). 745. 
708. Colymbetes ambiguus, Say, Agabus ambiguus, M.C.—Ovalis, vix convexus, 
niger, elytris rufescentibus, antennis pedibusque rufis, his femoribus nigricantibus, 
prothorace margine laterali haud lato; prosterni processu elongato, angusto, 
acuminato, lateribus sat compressis, punctulatis. Long. 6}, lat. 37 m.m. 
I have seen but two specimens in bad condition, and find the only important 
difference from Dytiscus congener, to be the more carinate and less smooth 
prosternal process; I have not seen the female: the male has the tarsi formed as 
in Dytiscus congener (No. 706); I shall not be surprised if the examination of 
other individuals, show this supposed species to be not distinct from Dytiscus 
congener. 
The identification with Say’s description is by no means a certainty. A specimen 
was sent me by Leconte as being his A. morosus. 
North America, (California), 746. 
- 709. Agabus mutus, n. sp.—Ovalis, parum convexus, nitidus, haud reticulatus, 
nigricans, elytrorum lateribus dilutioribus, prothorace subsenescente, antennis pedi- 
busque rufis. Long. 63, lat. 32 m.m. 
The male has the basal joints of the front and middle tarsi scarcely incrassate, 
and having therefore a very small area beneath furnished with sexual clothing: 
the front claws are a little longer than in the female, nearly straight, and a little in- 
crassate or laminate ; the female is rather duller than the male but has no reticulation. 
The species is closely allied to Dytiscus congener (No. 706), but is rather smaller 
