Cutaneous Glands in the Terrestrial Isopoda. 217 
SrructureE In Porcerzio prraratus, Larr. 
For the purpose of a preliminary study of the distribution 
and histological structure of these glands, the species 
Porcellio dilatatus, Latr., was chosen, although many other 
species have been examined ; but uniess otherwise stated the 
following description and remarks apply to that species. 
Apart from dissection, trausverse, longitudinal, and 
horizontal sections have been made, aid various methods 
Spe 
Typical appearance of a cutaneous gland and 
excretory canal in section. 
adopted for the examination of the pleural plates of the 
segments. A modification of that described by me in 1918 
(1) has given very satisfactory results. 
In form the glands vary in size and shape according to 
their period of development, but a typical fully developed 
gland consists of a somewhat spherical mass with a series of 
Ann. & Mag. N. Hist. Ser. 9. Vol. vii. 15 
