22 



ADEPHAGA. 



inferring tliat the peculiar sculpture of the females bears no correlation 

 to the development of the male tarsi." 



A. uliginosus, var. 9 dispar.. Bold. Zoologist, app. xxiv., 1849. 

 This is the dull variety of the female which I have recorded as not 

 uncommon in Ashham Bog, York (Brit. Col. i. p. 192) ; Dr. Sharp 

 (Dytiscidfe, p. 507), speaking of A. uliginosus writes: " The female 

 generally resembles the male in sculpture, but a form occurs rarely 

 (? in Britain only) in which the upper surface in this sex is excessively 

 densely and finely reticulate, so as to be quite opaque " (v. Donisthorpe. 

 Ent. Kecord, xi., 1899, 160). 



A. affinis, Payk ; A. unguicularis. Thorns. There has always 

 been great difficulty with regard to the separation of A. affinis, Payk 

 and A. unguicidaris, Thoms., but this has been cleared up by an 

 excellent paper on the two species by Mr. F. Balfour-Browne (Ent. 

 Record, xviii., 1906, 273); in any case the species require careful 

 microscopical examination before they can be definitely separated. 

 The following is Mr. Balfour-Browne's summary of the distinctions : 



1. Form more parallel, colour black; 



metasternal lacinise or wings less 



sharply pointed ; reflexed margin of 



elytra black, and apex more sharply 



pointed. In male, anterior claw on 



anterior tai-si with a triangular tooth, 



the apex of which is directed neither 



forward nor backward ; stridulatory 



files shorter, with ridges very fine and 



close together. Less reliable char- 

 acters ; legs more inf uscate ; antennfe 



less inf uscate; occipital spots more 



distinct ...... 



Form more oval ; colour of a slightly 



feneous cast ; metasternal lacinise or 



wings more sharply pointed ; reflexed 



maigin of elytra obscure-red, and 



apex less sharply pointed ; in male, 



anterior claw on anterior tarsi with a 



tooth, in which the apex is directed 



forwards towards the apex of the claw ; 



stridulatory files longer, with ridges 



stronger and farther apart. Less reli- 

 able characters ; legs less infuscate ; 



antennai more infuscate ; occipital 



spots less distinct .... A. unguicularis, Thoms. 



Roughly speaking, .4. rt/?t>zi,s- is a Scotch species ^n^l A. unguicidaris 

 an English species. Mr. Balfour-Browne says that he has taken the 

 latter not uncommonly in East Norfolk and near York, and the 



A. AFFINIS, Payk. 



