A HISTORY OF DERBYSHIRE 



title suits and was perhaps suggested by its usually slow reluctant move- 

 ments. It has but little tendency to double itself up, and when the 

 maternal pouch is crowded with young such a feat would be out of the 

 question. In common with the species next to be mentioned it has a 

 character that is of much service in classifying specimens. In woodlice 

 the first antennae are inconspicuous, but the second make a good show. 

 When these are examined they are found to have a five-jointed peduncle 

 followed by a variously sub-divided flagellum or lash. The whip-like 

 character of the latter is to a great extent lost in most inland forms 

 because the sub-divisions or jointlets are very few. In Oniscus and 

 Philoscia this flagellum is three-jointed, but it is only two-jointed in 

 the other genera which will here be claimed for Derbyshire. Our next 

 species then, Philoscia muscorum (Scopoli), cannot be distinguished from 

 Oniscus asellus by counting the joints of the antennae, but it is very much 

 smaller, much more lively in its movements, and much brighter and 

 more varied in its colouring. It has also high up on each of its pale- 

 coloured legs a dark spot which is additionally distinctive. Moreover 

 the relation of the tail part to the trunk sets Philoscia apart from all the 

 three other genera of the present notice, for it has the pleon abruptly 

 and continuously narrower than the middle body. In the others the 

 abruptness of the narrowing is masked, because the third pleon-segment 

 widens out over the lateral extremities of the first and second, so that 

 its side margins form a fairly continuous line with those of the central 

 trunk. The third species is Porcellio scaber, Latreille. This is just as 

 common and plentiful and widely distributed as the other two. It com- 

 petes in length of body but not in breadth with Oniscus asellus ; it is 

 much rougher with its many rows of tubercles, and usually, but not 

 always, much darker and more uniform in colouring. The two-jointed 

 flagellum of the antennas prevents any confusion with the preceding 

 species. 



The second family owes its name to the genus Armadillidium, Brandt, 

 which contains two Derbyshire species. One of these is A. vu/gare 

 (Latreille), of which some characteristics have been already indicated. 

 Until recent years this was the only species of its genus, as it still is by 

 far the commonest, known in Great Britain and Ireland. It has now 

 three companions, the latest added being A, pulchellum^ Brandt, con- 

 cerning which Dr. R. F. ScharfF writes in the Irish Naturalist for May 

 1 90 1 1 : 'I discovered this species in April close to the village of Bally- 

 mote (co. Sligo) when visiting the district for the Royal Irish Academy 

 Fauna and Flora Committee. I found about a dozen specimens, all full- 

 grown about 5 mm. in length under stones on the top of a mud wall ; 

 it was there in company with the very common grey woodlouse, Por- 

 cellio scaber. The next day we kept a good look out for the species in 

 the neighbourhood, but only met with some of the common kinds. A. 

 pulchellum is a distinctly northern species, having been taken in Scandi- 

 navia, northern Germany and Belgium.' When thanking Dr. ScharfF 



1 Vol. x. p. 109. 

 106 



