PRACTICAL HINTS. 



187 



Agabns unguicularis, Thorns, and A. affinis, Payk. 



By JAMES EDWAEDS, F.E.S. 



After a careful perusal of Mr. W. E. Sharp's elaborate article on 

 these two species {antca, pp. 90-92) 1 find myself fully able to agree 

 with him that the result of his investigation into the subject is not 

 quite so satisfactory as could have been desired. So far as I can 

 gather he intends to use the name affinis for the species taken by Dr. 

 Sharp and the late Mr. Lennon near Dumfries ; and unr/uicidariii for 

 the more widely distributed species long known to us under that name, 

 but, in dealing with the insects themselves, my experience is not quite 

 the same as his. In his affinh the male has the outer anterior tarsal 

 claw armed with a very distinct large sharp tooth which extends to the 

 middle of the claw ; this may apply to affims, W. E. Sharp, but in 

 affinis, Payk., as I know it (I speak of Dumfries specimens ex Lennon) 

 the position of the tooth is practically basal, i.e., distinctly before the 

 middle of the claw, and in shape it is a triangle as high or higher than 

 its width at the base. In Mr. Sharp's umiiiiciilans the male has the 

 anterior tarsal claws with an inconspicuous tooth at the base ; but in 

 unguicularis, Thoms., as I know it (I speak of Norfolk specimens) there 

 is a tooth on one anterior tarsal claw only, and its position is practi- 

 cally midway between the base and apex of the claw, whilst its shape 

 is that of a triangle not so high as its width at the base. One hardly 

 likes to think that so careful a worker, after elaborating his subject 

 through two pages of print has finished by transposing the names of 

 the species dealt with, and yet something of the kind seems to have 

 happened. 



As bearing on the question of distribution and the differences in 

 the stridulatory organs, it may, perhaps, be well to transcribe the 

 following passage from my " Supplementary List of Norfolk Coleoptera" 

 {Trans. Norf. and Nonrich Nat. Soc, 1898-9, p. 523) " Agabus affinis, 

 Payk. — This species must be expunged from our list ; my Brandon 

 specimens proving to be unguicularis, Thoms. The unsatisfactory 

 nature of the characters given for the separation of these two species 

 in the English text-books led Mr. Thouless to make a critical examin- 

 ation of authentic specimens of the males of each, and it is clear from 

 the material prepared by him that the striae in the series forming the 

 stridulatory organ on each side of the third ventral segment of the 

 abdomen are about twice as numerous in affinis as in unguicularis ; the 

 oedeagus of the former, too, has, in the lateral aspect, a distinct angular 

 projection near the middle of its upper edge, which is entirely wanting 

 in that of the latter." 



With regard to these Brandon specimens, I should add that, so far 

 as I am aware, Mr. Sharp sought no opportunity of seeing them. 



J^RACTICAL HINTS.* 



Field work for June and early July. 



By J. W. TUTT, F.E.S. 

 1. — The full-fed larvae of Nola strigula are to be obtained in early 

 June feeding on oak, principally on the under cuticle of the leaves. 



' " Practical Hints for the Field Lepidopterist," Pts. I and II each contains 

 soaie 1250 practical hints similar to these, but relating largely to the Macrc- 

 lepidoptem. luteiieaved for collector's- own ivotee. Price 66. each part. 



