216 Dr. W. E. Collinge on the 
They are derived from the conjunctive tissue. 
Nebeski (7) in 1880 pointed out that there were light and 
dark coloured cells among the species he studied, and Ide 
confirmed this, suggesting that tle larger the cells are, the 
more the division into two zones is acceutuated. 
In 1891 (4) Ide briefly described these glands in Oniscus 
asellus ; he states “ that they are present in the uropoda and 
the last three abdominal segments, the canals of which are 
all directed towards the cuticle of the uropoda. The urostyle 
(=the expodite) is entirely filled with these glands and a 
series are situated by the side of the intestine. Each gland 
opens separately and their orifices are disposed in two or 
three rows.” 
There are four nuclei, he states, in each cell. Two, seen 
by Huet, containing large nucleoli and a network not very 
rich in nuclein, are lodged in the secreting mass itself. The 
third nucleus is small and oval; it is found almost between 
the two first on a level with the union of the excretory canal 
with the principal mass. A fourth nucleus is constantly 
met with on the excretory canal itself. It is extremely 
flattened® and scarcely surrounded by a thin protoplasmic 
layer. 
"There is considerable variety in the form of the glandular 
cells, and there is no vestible in the cells as described by 
Huet. The glands produce a viscous material, which takes 
the form of very tenuous but rather resistant filaments. 
It will be noticed that Ide makes no mention of any glands 
in the mesosome. 
Finally, in 1907, Verhoeff (8) very briefly pointed out 
the distribution of these glands in numerous genera, and 
endeavoured to utilize the position of the pores for syste- 
matic purposes. In spite of the very brief and fragmentary 
descriptions given by this author, he was the first to 
reconize the true segmental nature of the cutaneous glands, 
and regarded it as a primitive feature in the organization of 
the Isopoda. 
Terr OccURRENCE IN THE ONISCOIDEA. 
To what extent these glands occur in the Oniscoidea it is 
at present difficult to say. I have satisfied myself of their 
presence in the following British genera :-—Ligidium, 
Trichoniscus, Oniscus, Philoscia, Porcellio, Porcelhonides, 
Cylisticus, and Armadiilidium. They are also present in 
Cubaris, Hemilepistus, and other exotic genera—indeed, I see 
no reason to doubt their presence in most, if not all, of the 
genera of this Order that are purely terrestrial in habit. 
