164 i J^y. 



a foreign origin. Mr. J. E. Collin communicated " Notes on the Value of the Geni- 

 talia of Insects as Guides in Phytogeny," by Mr. W. Wesche, F.R.M.S. Dr. D. 

 Sharp communicated a paper " On certain Xgcferibiidx, with descriptions of two new 

 species from Formosa," by Mr. Hugh Scott. Dr. J. Hancock, " Further Studies of 

 the Tetriginx (Orthopterd) in the Oxford University Museum." Mr. J. C. Moulton, 

 " Mimicry in Tropical American Butterflies." Professor E. B. Poulton, " Heredity 

 in Papilio dardamm from Natal, bred by Mr. G. F. Leigh, F.E.S., of Durban," 

 and exhibited, in illustration, a large series of the forms of P. dardanus 

 from Natal and Chirinda. Mr Hamilton H. Druce, " New Species of Hesperiidse 

 from Central and South America," and exhibited the specimens described ; also 

 a series of the sub-family Pgrrhopgginx, together with the genus Ergcides of the 

 sub-family Hesperiinx showing the great similarity of some of the species with 

 those of the Pyrrhopygine genus Jemadia, and also pointed out that the sub-family 

 PamphiUnx contained genera with species again almost exact copies of those shown 

 in the two previously mentioned sub-families. Dr. G. B. Longstaff called the 

 attention of Fellows to a very interesting paper on " The Life-History of House 

 Flies," by Dr. A. GrifBth, in the monthly publication of " Public Health." — 

 J. J. Walker, Hon. Secretary. 



ON THE BRITISH SPECIES OF PSORA (Part II). 

 BY JOHK H. WOOD, M.B. 



The smaller the forms of life, the more numerous, as a rule, are 

 the species. And so in this genus PJwra, whilst the larger and more 

 specialized species (Group I) are fairly manageable, the smaller and 

 simpler ones (Group TI) are well nigh overwhelming in number and 

 variety. Here in this small corner of the county of Hereford I have 

 myself picked up about ninety distinct and well-defined species 

 belonging to the latter (iroup, in fact, all those, with but few excep- 

 tions, treated of in this paper. Nor does this number, great as it is, 

 exhaust even my own neighbourhood, for other forms have been kept 

 back which, either from the want of some good structural character 

 or from scantiness of material, it would at present be unwise to name. 

 What, then, will be their number when there are more workers in the 

 field and the gathering ground is wider ? 



In dealing with so huge an assortment of closely allied forms, it 

 becomes absolutely necessary to divide them up, if possible, into 

 Sections. Yet to this end the very simplicity of their structure offers 

 a serious impediment ; and in place of the absolute characters that 

 were found so useful in the earlier Group, we have now to depend 

 upon comparative ones mainly. There is, it is true, the undivided 

 second thick vein (Section A) as in Group I, but it helps little here, 

 and marks off only a single species, Verrall's formicarum, which may 



