74 M. Hesse on a new Parasitic Crustacean. 
The abdominal segments, when in their normal state (that is to 
say, neither much contracted nor much extended), are perfectly 
distinct from each other ; they decrease in depth and width from 
the base to the apex, and are nearly square, being only a little 
narrower above than below. The last, or sixth, does not at all 
resemble the others in its form, which is nearly that ofa shield, 
widened at its base, slightly emarginate at the sides, and termi- 
nated by two obtuse points furnished with a few hairs. Seen in 
profile, they show between them a cavity in which the anal 
orifice opens. However, these forms, which are well marked 
when they are in their normal state, are extremely variable and 
become considerably modified according to circumstances. 
The head, seen in profile, has the frontal margin truncated at 
the apex and rounded and bent downwards at the sides. Upon 
it we perceive the antenne, which are thick, short, cylindrical, 
and composed of two or three joints, terminated by divergent 
hairs. Starting from the antenne, the outer margin of the 
cephalic envelope descends obliquely in a straight line to go to 
the superior angle formed by the inflation presented by the 
orifice of the cesophagus. 
Between these two points is the buccal orifice, which is placed 
in the centre of a circular platform slightly hollowed in the 
middle. This apparatus, which is very complicated, presents 
the following arrangement :—Immediately below the antenne, 
and at the sides of the epistome, there are two pairs of footjaws, 
which are solid, pectinated, and terminated by a hooked claw; 
then follows, in the middle, the buccal aperture, composed of a 
conical proboscidiform tube, which issues from and returns mto 
a cavity formed in the centre of the platform. This tube, which 
is constructed of a very firm, but very delicate and transparent, 
membranous tissue, receives its impulsion from two pairs of 
footjaws, one superior and one inferior, which keep it extended 
or contracted according as this organ issues from or re-enters 
the cavity destined for its reception. When the tube is entirely 
out, we may perceive in its interior a conical appendage, rounded 
at the end, ascending and descending frequently, like the piston 
in the chamber of a pump: this is really the mouth with its 
mandibular armament. 
The latter is formed of two pairs of footjaws, which are denti- 
culated and trenchant, and furnished with a corneous substance; 
these, by applying themselves together, can seize and triturate 
objects. They are, moreover, surrounded by a soft and mobile 
labial margin, which seems to cover them when necessary ; 
lastly, within these organs we see some mandibular palpi, com- 
pleting this system, which may be employed, according to cir- 
cumstances, both for suction and mastication. 
