S-i [April. 



even in tlie freshest specimens. In this respect the species is much less 

 constant than tlie allied P. vesfalis. 



6 6. 



1 (2) FoLirtli, fifth, and sides of sixth segment yellow 



. . . .var. a (Perthshire). 



2 (1) Tail white, at most with yellow hairs dividing it from the black 



preceding segments, or the tail may he sordid or infiiscate. 



3 (G) Tail white or sometimes more or less dull yellowish white or suh- 



olivaceous. 



4 (o) A conspicuous yellow anterior hand on tlie tliorax 



. . . .var. ji (the ordinary form). 



o (4) The yellow hairs of the thorax so much mixed with bbick that the band 



is obscure. (In this form the hairs of the basal abdominal segment 



are often black or very sooty and the tail less distinctly white, but 



these characters maj' appear in samples, which have the thoracic 



band yellow) var. y. 



6 (3) The tail, though paler tlum the rest of the abdomen, is sordid fuscous, 

 and this colour is less extended basally than the white of normal 

 specimens var. S ( Yorksiiire). 



??• 



1 (0) Middle and hind metatarsi chiefly black haired, not nutiibly red to the 



naked eye. 



2 ( o) Thoracic band uniformly coloured throughout. 



3 (4) This hand paler yellow and the tail whiter, var. a (n(n-uial form). 



4 (3) The band more brownish yellow, not differing much from some 



examples of restalis, the pale tail of the abdomen less white (more 

 sordid) var. j3 (Cumberland). 



5 (2) The thoracic band more or less mixed witli black hairs in the middle, 



so as to lead one to expect that it may be actually interrupted at 

 that point in some specimens var. y. 



6 (1) Middle and hind metatarsi to tlie naked eye notably red-haired, the 



hind tibiae also more or less similarly clothed ; size very small, no 

 larger than an average-sized male var. uov. subnijlpes. 



The yellow-tailed form of 6 var. a I have never met with where I 

 have collected the species in N. Wilts, Gloucestershire, and Devon, but 

 it is recorded in Sladen's book. 



Tlie variety of tlie § which I have ventured to name has been 

 taken in two localities in Wharf edale, and when the first example — from 

 Grassington — was sent to me for inspection by Mr. K. Butterfield, 

 I suspected it might prove to be parasitic on JBomhiis soroensis. 

 Mr. A. E. Bradley, who submitted the second, which was taken by 

 Dr. W. J. Fordham at Ilkley, on the edge of Romhald's Moor, tells me 

 that in this locality also B. soroensis is numerous. One of my Devon 

 examples is hardly bigger than these specimens, but otherwise it is quite 

 normal. 



