NEW BRITISH SPECIES, ETC., IN 1868. 23 



with G, 7narinus. He states it to be very closely allied to 

 G. marinus, but, on the average, considerably smaller, with 

 '^he strise finer, especially the inner ones. It appears to have 

 a dull, opaque var., ^nd to have been recorded as British by 

 SufFrian twenty-five years ago. 



From Dr. Sharp'sremarks it would seem that the boundary 

 line between the two species is very problematical. 



In Mr. Crotch's Cat. " dorsalis'' is given as a var. of G. 

 mat^nus. Aube quotes it as distinct (it appears to be 

 opaque, with a ferruginous spot on the centre of the elytra, 

 divided by the suture), and gives opacus as an entirely dark 

 var. of it, and Thomson unites both as vars. b and c of 

 marimis. 



18. Gyrinus ^neus, Stephens, Mand., ii, 95; id., Man., 

 78; Aube, loc. cit.,690. 



This insect, described by our countryman and adopted by 

 Aube (who quotes it from England), is by the latter stated 

 to be very like marinus, but more convex, of a more bril- 

 liant and blueish black, with the punctuation of the elytra 

 generally smaller and increasing in size as they get further 

 from the suture, and the apex of the elytra more squarely 

 cut, the external angles being not at all rounded. It appears 

 also to be rather smaller than G. ma7'inus. 



Thomson, Skand. Col. ii, 116, adopts Aube's cBneuSy but 

 says it is much less than marinus, narrower, entirely brassy 

 above and with its forehead scarcely bifoveolated. The apex 

 of the elytra he describes as obtuse, and the striae as equal, 

 all distinct, with their interstices very delicately sub-strigose. 

 The reflexed margins, moreover, are nigro-aeneous in the 

 latter's species and aeneous in Thomson's. It seems, there- 

 fore, impossible that his insect can be identical with that of 



