218 
CRUSTACEA, 
inhabit the bodies of various Acephala or Linnsean Medusae, and of 
some otlier Zoophytes. 
Here, as in 
PllRONIMA, Lat., 
There are but two — very sjiort and biarticulated — antennae ; the 
fiftli pair of feet is tlie largest of all and terminates in a didactyle for- 
ceps ; the six appendages of the extremity of the tail are styliform, 
elongated and forked or bidentated at the end ; six vesicular sacs may 
be observed between the last feet. Several species appear to exist, 
but they have not been strictly and comparatively described. 
That which has been taken for our type is the Cancer seden- 
tarius, Forsk., Faun. Arab., p. 95 ; Latr,, Gener. Crust, et In- 
sect. I, ii, 2, 3, which is found in the Mediterranean, and inha- 
bits a membranous transparent body that has the figure of a cask, 
and which appears to proceed from the body of a species of Beroe. 
The Phronime sentinelle, Risso, Crust., II, 3, inhabits the 
interior of Medusae, constituting the genera Equoree and Geronie 
of Peron and Lesueur. Another species, according to Leach, has 
been observed on the coast of Zealand. 
There we observe four antennae, ; all the feet are simple ; on each 
side of the extremity of the tail is a lamellated or foliaceous fin, the 
leaflets of which are acuminated or unidentated at the end. 
Hyperia, Lat. 
The body thickest anteriorly ; the greater portion of the head occu- 
pied by oblong eyes somewhat emarginated on the inner edge ; two 
of the antennae, at least half as long as the body and terminated by a 
long setaceous stem composed of several small joints *. 
Phrosine, Risso. 
Form of the body and that of the I.ead similar to the Hyperiae, but 
the antennae, at most, the length of the latter, composed of but few 
and styliform joints, or terminated by a stem resembling an elongated 
cone f . 
* Cancer monaruloides. Montag., Trans. Lin. Soc. XI, ii, 3 ; — Hyperie de Le- 
sueur, Lat., Encyclop. Method., Atl. d’Hist. Nat., CCCXXVIII, 17, IS; Des- 
mar. Consid., p. 258. 
N.B. Near the Hyperiae should he placed the genus Themisto, Lat., carefully 
figured and described in the Mem. de la Soc. d’Hist. Nat., tome TV. As in the 
Hyperioe, the eyes are very large and occupy the larger portion of the head ; trvo 
of the antennne (the inferior), all terminated by a multi-articulated stem tapering to 
a point, are evidently longer than the others. The part there called livre inferieure, 
is the ligula ; those v.’hich appear to form the third pair of jaws are the first of the 
foot-jaws, and, as in the Amphipoda and Isopoda, dose the mouth interiorly under 
the form of a lip. The four remaining foot-jaws are very short, directed forwards 
and laid upon the mouth in such a way that they seem to constitute a part of it, so 
that if we do not count them, or if we merely consider the following locomotive and 
much more apparent organs as feet, this animal, like the Hyperia and Phrosine, 
appears at the first glance to have but ten. feet instead of fourteen. The third pair 
of foot-jaws is terminated by a small didactyle forceps. The same pair of feet, pro- 
perly so called, is much longer than the others ; its penultimate joint is greatly 
elongated, and is armed with a range of small spines forming a sort of comb. But 
a single species is known. 
'I' Phros. macrophthnlma, Risso, Jour, de Phys., Octob. 1822 ; Desmar., Ib., p. 
259 ; Cancer galba, Montag., Trans. Lin. Soc., XI, ii, 2. 
