260 
that in this species the first scales of the peduncle develop very 
early, even before the all but single row of smaller latera com- 
mence to appear. The primordial plates are a little larger than in 
the preceding species; this seems to indicate that the pupa of Mi- 
tella mitella must be a little larger than that of Mitella polymerus. 
Mitella sertus (Darwin). 
Hen and Chicken Islands, Hauraki Gulf, New Zealand. On the coast 
below the rocks 30/XII 14. Numerous specimens. 
The numerous specimens give a rather good idea of the vari¬ 
ations of this species; partly the number of lower latera is found 
Fig. 21. Mitella sertus from Hen and Chicken Island, N. Z. a and b Capitulums of 
two adult specimens showing variation of the carina ; c mandible, d maxilla. 
[a—b x 1,5, c—d x 15]. 
to be very different, partly the shape, and arrangement of the 
capitulum plates also differ in different individuals (Fig. 21). The 
variations of the carina are especially obvious; in some specimens 
the carina is almost quite straight, with prominent apical part, in 
others it may be evenly curved with the apex between the hind 
margins of the terga. These extreme variants are linked together 
by a complete series of intermediate stages, and they cannot even 
be distinguished as different „varieties“, being merely accidental 
variants. — The variations of the present material tell us that 
Gruvel’s characteristic of the species (19.05) „la caréne qui est 
droite, å apex saillant en arriére des terga“ does not always hold 
good. This variability also justifies the doubts already uttered 
by Gruvel on the same occasion, whether Mitella Darwini ( Hut- 
