410 M. E. Hesse on the Pranizee and Ancei. 
styles which issue between the parts of the apex of the rostrum, 
and are probably employed in producing wounds from which 
the blood may flow. Behind the footjaws the lower part of 
the head exhibits a deep, longitudinal median fissure, which 
completes the mouth, and forms at its extremity a commissure 
destined to facilitate the introduction of fluids by suction. Below 
the mouth, in some individuals, there is a very prominent bilobed 
sac, forming a sort of crop, the office of which is unknown, 
although it appeared to contain food: its presence is the more 
remarkable as it occurs but rarely, and disappears when the 
Crustacean becomes converted into an Anceus. 
The thoraz, generally of an ovoid form, is equally convex above 
and below, and is covered with a transparent skin. It presents 
no well-marked segments, except the first and second, and 
sometimes the third, which are very distinct. The third segment 
is rarely entire; it is often indicated by two lateral pieces, 
different im substance from the skin upon which they are fixed, 
and which appear to be rudiments of the carapace. To these 
lateral pieces are united others, resembling the elytra of the 
Meloés and Hemiptera. Analogous pieces are also placed at 
the base of the other thoracic limbs, to which they serve as 
points of attachment; and, lastly, these are sometimes united by 
a sort of ridge, forming a narrow margin to this part of the 
body. The middle of the thorax, both above and below, presents 
vertical and transverse lines forming four divisions, of which the 
angles are truncated at the centre by a small lozenge-shaped 
piece ; these lines probably indicate the part at which the skin 
is divided when the animals undergo their last transformation. 
The /egs present no peculiarities requiring notice, with the 
exception of the first two, which are fixed on each side to the 
base of the head, the apex of which they scarcely pass; they are 
armed with strong claws, which enable their possessor to adhere 
firmly to any object. These legs, which constitute the first 
pair of thoracic members, makes the number of these twelve 
instead of ten, as has hitherto been supposed; but they are 
wanting in the Ancei. 
Structure of the male Ancei. 
In the transformation of the Pranize into Ancei, the only 
parts which undergo no metamorphosis are the antenne, the 
thoracic feet, and the abdomen. The head, on the contrary, 
shows the most extraordinary changes; from being very small, 
it acquires a volume at least equal to that of the thorax. From 
above, the head of the male Anceus is seen to be armed in front 
with two large moveable lamin, generally falciform and denti- 
eulated on their inner margin, and elevated at the apex, so as to 
