I2I 
THE TERRESTRIAL ISOPODA (WOODLICE) 
OF YORKSHIRE. 
F. RHODES, 
Cartwright Hall, Bradford, 

(Continued from page 102). 
Genus Oniscus Linne. 
ONISCUS ASELLUS Linne.—Common everywhere. 
Genus PurLosciA Latreille. 
PHILOSCIA MUSCORUM Scopoli.—This species is recorded 
by the Rev. T. R. R. Stebbing as occurring at Naburn Hall 
(Victoria County History of Yorks.). 
I find it to be generally distributed and common in suitable 
localities. Its favourite habitats are in damp woods, on hedge 
banks, among moss, dead twigs, and fallen leaves. It is not 
uncommon on the grassy margin of the canal banks; under the 
decaying leaves of herbaceous plants on railway banks, and 
in the open fields. 
This species is variable in colour; in the woods on the 
mountain limestone districts it is generally light grey with 
yellow, pink, or red markings, while on the Millstone grit 
areas of the west Riding, it is generally very dark grey with 
almost obscure darker markings. 
Wharfedale, T. Stringer, May, 1909; Ben Rhydding, May, 
1909; Canal Banks, Keighley, 1909; Castle Hill and Grim- 
bold’s Crag, Knaresborough, August, 1910 ; Gisburn, Septem- 
ber, 1911; Harewood, Yorkshire Naturalists’ Union visit, 
May, 1911; Addingham, September, 1911; Steeton, Bingley 
and Saltaire, August, 1911 ; Elks Wood, Ingleton, May, 1912 ; 
Whitby Cliffs, R. S. Bagnall, March, 1912; Malham, May, 
1912; Forge Valley, Lady Edith’s Drive, and Castle Hull, 
Scarborough, August, 1913; Canal Side, Wakefield, 1913. 
PHILOSCIA MUSCORUM var. OBSCURA Scopoli.—This is the 
most common form, on the Millstone grits of the West Riding. 
PHILOSCIA MUSCORUM var. FLAVA Bagnall.—I have taken a 
yellow form with grey markings in Elks Wood, Ingleton, 
which may be referred to this variety. 
Genus PORCELLIO Latreille. 
PORCELLIO SCABER Latreille.—Porcellio scaber is one of the 
common species, and is to be found in any suitable place. It 
can adapt itself to very varied conditions, either in very damp 
places or on the top of dry limestone walls. 
It would be useless to give localities for this species, as it 
seldom fails to turn up when one is out collecting. I have 
1916 April 1. 
