P I8r 
THE BRISTLY MILLIPEDE IN EAST YORKSHIRE. 
[. STAINFORTH, B.A., B.Sc., 
Hull. 
IN searching among debris at the foot of larch trees in the 
higher part of Brantingham Dale, East Yorkshire, on Good 
Friday, I met with numerous examples of the Bristly Millepede, 
Polyxenus lagurus. Besides being one of the smallest of our 
indigenous millepedes, adult specimens reaching a length of 
about one eighth of an inch only, Polyxenus is peculiar in 
possessing bundles of bristles on each of its ten body segments, 
and differs in other important respects from normal Diplopods. 
So marked are these differences that the 
Polyxenide form a_ separate sub-class 
(Pselaphognatha) of the Diplopoda, of 
which P. lagurus is the only British repre- 
sentative. The accompanying illustration, 
which is reproduced by permission of the 
Trustees of the British Museum, from the 
“ Guide to the Crustacea, Arachnida, Ony- 
chophora and Myriopoda’ (p. 121), gives a 
very good idea of the appearance of this 
creature. 
It is interesting to know that many 
of the early fossil species of millepedes are 
protected by bundles of bristles similar 
to those of the Polyxenide, and it is prob- 
able that the family is an ancient one. 
Polyxenus lagurus is said usually to occur 

under the bark of trees. A writer in Pelpsenne cures: aie 
Science Gossip, 1872, p. 31-3, recommends 
searching under the loose bark of old yew trees, and Dr. A. R. 
Jackson (Myriapoda of the Chester District, Lancashire Nat. 
1914, p. 453) records them from under the bark of oak trees, 
while in an article on ‘The Pencil-tail (Polyxenus lagurus),’ 
appearing in The Journal of the Quekett Microscopical Club for 
1870 (p. 110), S. J. McIntire writes that ‘pencil-tails inhabit 
the bark of the willow, the elm, and the apple-tree.’ At 
Brantingham Dale, however, I could not find any under 
loose bark, though they doubtless occurred in such situations, 
but specimens were easily found by shaking the debris at the 
foot of the larch trees, over a sheet of paper, the little animals 
being readily recognised as they glided briskly along on their 
thirteen pairs of tiny legs. On visiting the locality again on 
May 14th, Mr. H. M. Foster and I had precisely the same 
experience. We could find numerous examples of all ages and 
sizes among the grass, moss, etc., a foot away from a certain 
tree, but not one under bark. McIntire writes that he found 


1916 June 1. 
