412 M. EK. Hesse on the Pranizee and Ancei. 
The generative organis situated at the extremity of the thorax, 
above the abdomen: it consists of a long penis, showing 
throughout the course of the canal which traverses it. This 
penis is in the median line of the thorax ; its base is formed by 
the first branchial feet, and it is protected above by a sort of 
cup formed by a fold of skin. This cup seems to be destined 
to receive the laminz of the branchial false feet when they are 
raised over the thorax, and by this combination the generative 
organs are completely protected. 
This structure is common to all the species, and the organ 
only varies in form. Thus in Anceus Manticorus the penis is 
greatly developed, and consists of a long erectile tube diminishing 
from the base to the apex, with a central canal traversing it from 
end to end. It is truncated at the apex, which is surrounded by 
a thickened portion notched in the middle, the extremities of 
which form two valves or excitative organs. In Anceus Briva- 
tensis the tube is not so long, and appears to be articulated and 
capable of being invaginated in the lower parts; the extremity 
is also furnished with two lateral prehensile or excitative organs. 
In Anceus Trigl the penis is short, tubular, and inflated in the 
middle. 
Structure of the Female Ancei. 
The female Ancei are so different from the males that, without 
tracing their transformations, their connexion could not have 
been suspected. The head, instead of being of considerable 
size, as in the males, is very small, and is moreover deprived of 
the two large mandibles; the thorax, instead of being cylindrical 
and elongated, formed of distinct segments and divided into two 
parts by a constriction, is oval, flattened at the sides, inflated in 
the middle, and as it were deformed by the great quantity of 
ova which it contains. 
The head, seen from above, is globose in the centre, flattened 
at the margins, broad at the base, and truncated at the apex. 
It has no apparent neck, but is deeply inserted between the two 
anterior processes of the thorax. Transverse lines in the thorax 
indicate its division into five segments; all round the thorax is 
a broad margin, which serves for the attachment of the five pairs 
of legs. The eyes are pretty large, and placed at the origin of 
the antenne. 
Seen from beneath, the head presents, first of all, two footjaws 
of the first pair, which origimate beneath the eyes, and consist 
of four broad joints of equal length, but diminishing in width 
from base to apex. The last joint is rounded at the end, and 
bears some hairs. These two footjaws meet in the median line 
of the head, and pass its apex a little. Beneath these is the 
