320 



[November, 1915. 



des coridon, ab. semisyngrapJia, blue suffused females of Polyommatus icariis and 

 an ab. syngrapha with very dark margins to the wings. Mr. H. Moore, imagines 

 of the pylades groi^p of Papilio from Africa, and read notes. Mr. "West 

 (Greenwich), the rare Coleopteron, Athous rhomheus, taken at Ascot during the 

 field-meeting on Jiily 3rd. Mr. B. S. Williams, an aberration of Eupithecia 

 siihnotata in which the mottled markings were absent, there being present on 

 the sub-marginal area a series of quadrate light spots. — H. J. Turner, Hon. Se*-. 



NOTES ON BEITISH PHILYDRUS.-lso. 2. 

 BY D. SHARP, M.A., F.R.S. 



Since I wrote the notes published under this title last year (Ent. 

 Mo. Mag., L, p. 80) some additional and important information has 

 been obtained, and the notes now offered are intended to set this 

 forth. 



As I have invoked the aid of the male genitalia, I will begin with 

 an explanation of them which will, I hope, be made comprehensible by 



the accompanying figures. The 

 aedeagus of Philydrus is of the 

 kind normal in the sub-family 

 Hydrophilini, and when taken 

 out it looks so much alike in the 

 various species as to suggest that 

 it is of little value for their dis- b 



crimination. This, however, is not the case, as 

 the median lobe affords important characters, 

 though unfortunately these cannot be seen until 

 it is dissected out from the lateral lobes, which 

 are so voluminous as to enwrap and obscure 

 the median lobe. A dissection is necessary to 

 extract the lobe, and as this involves a some- 

 A what delicate operation, the value of the struc. 



ture for practical determination of species is somewhat detracted from. 



The basal piece is large, and extends over more than one-half of 

 the diameter of the tube, and has the anterior part of an unusual and 

 rounded form, a peculiarity characteristic of all the members of the 

 genus, and I believe found only in its limits. The lateral lobes are 

 large and differ but little in the various species. The median lobe when 

 extracted is found to consist of a dorsal and ventral blade, connected 



