NEW BRITISH SPECIES, ETC., IN 1863. 21 



14. Gyrinus distinctus, Aube, Icono(y., v. 385; Hydroc. 



et Gyr., 666; Suflr.; (Kies.) Scliaum, 1. c, 141. 



Dr. Sharp, loc. cit., records his opinion that this insect is 

 only a variety of G.'bicolor, Payk., and that it usually re- 

 presents that species in our collections. The type hicolor^ of 

 which Mr. Bold has a few specimens taken in Durham, and 

 which is also in Mr. G. R. Crotch's collection, is lar<jer than 

 the insect above alluded to as G. distinctus, and has the 

 sides more parallel, and the elytra lonsjer, with the apex of 

 each individually more rounded, whereby the external an^le 

 is moi-e evident in the latter. But Dr. Sharp states that 

 variations in all these points occur. 



From Aube's account his distinctus is like nataior, from 

 which he states it to differ in its rather more elongate and 

 less regularly ovate fornl, its elytra being slightly obconic; 

 and by the reflexed part of its thorax and elytra, and es- 

 pecially its breast and the apex of its abdomen, being always 

 darker. He does, not mention it in connection with Irlcolor, 

 from which he separates it by seven other species. De 

 Marseul places it immediately next afier natator and before 

 cohjmhus in his Catalogue. Kiesenwetter's distinctus is 

 evidently the same as Aube's: he thinks it probable that 

 it may be conspecific with caspius. The brackish- water 

 insect hitherto known to me as bicolor seems to me to agree 

 better with caspius than distinctus. 



15. Gyrinus caspius, Menet.; Aube, Hydroc. et Gyr., 



679; Suffr.; Kies., 1. c, 140. 



Dr. Sharp, loc. cit., records two female specimens in Mr. 



G. R. Crotch's collection, which he attributes to this species, 



stating that it very closely resembles his distinctus, but is 



not so shining, having the interstices obsoletely but thickly 



