20 COLEOPTERA., 



continental types from Mr. Crotch, with whicli his insect is 

 stated to agree in every respect, save in its slightly smaller 

 size. Mr. Bold remarks that it closely resembles H. tristis, 

 but is rather larger, flatter, and more obscure than that 

 species, with a wider head and thorax and more pubescent 

 elytra. The angle formed by the junction of the sides of the 

 elytra with the sides of the thorax appears, also, to be still 

 more obtuse. 



13. Gyrinus natator, Auct. 



Dr. Sharp, in his excellent paper on our Gyrlnidce re- 

 ferred to in my introductory remarks, notes tlie occur- 

 rence in Britain of two well-marked races of this insect, 

 considered by Erichson and Suffrian as distinct species, 

 viz. : — 



{a) G. mergus, Ahr., N. Schr. Hall. Nat. Ges., ii, 43. 

 Broad, not so much narrowed before and behind, the inner 

 striae evidently finer than the outer, especially towards the 

 suture, but always distinct and perceptible for their whole 

 length ; common in the south of England, but not occurring 

 in Scotland. Kiesenwetter, 1. c, states this form to have 

 the breast and apex of abdomen ferruginous. 



{})) G. natator. Nari'ower, the sides more rounded, and 

 the internal strisg very obsolete or entirely wanting towards 

 the base ; abundant in Scotland, rare further south. 



To the above forms Aube adds another, the marginatus 

 of Germar, in which the breast and apex of abdomen -are 

 black. 



Dr. Sharp also records, from Deal, a small series of speci- 

 mens agreeing closely with each other, and possessing the 

 form of {}}) with the punctuation of («). 



