246 
CRUSTACEA. 
ternally, but are turned up, applied to tlic posterior sides of the body 
in order to support the ovaries, and terminate in two very small 
hooks *. The body presents no distinct articulations, and terminates 
j)Osteriorly in a kind of soft tail which is doubled underneath, with 
two conical or setaceous threads furnished with three setae or hooks 
at the end, directed backwards and issuing from the shell. The 
ovaries constitute two large, simple and conical vessels forming a 
cul-de-sac at their origin and situated on the posterior sides of the 
body, underneath the shell, and opening, side by side, in the ante- 
rior portion of the abdomen where the canal formed by the tail estab- 
lishes a communication between them. Tlic ova are spherical. These 
Crustacea spawn, and change their skin, as frequently as the Cy- 
clopes and other Entomostraca, and their mode of life is the same. 
Ledcrmuller states, that he observed them in coitu. Modern natur- 
alists, who have most closely studied them, however, have never 
been able to discover their sexual organs with certainty, nor been 
fortunate enough to see them in actu. M. Straus observed, under 
the origin of the mandibles, the insertion of a stout conical vessel 
filled with a gelatinous substance, which appeared to communicate 
with the oesophagus by a straight canal, that he suspects may be a 
testis or salivary gland. The individuals which were the subjects of 
these observations having ovaries, the Cyprides according to the first 
suppositi(m must be hermaphrodites. This is so much the more 
doubtful, however, as he himself remai’ks that it is possible the males 
may only exist at a particular season of the year, and that the vessel 
alluded to seems to be more nearly connected with the function of 
digestion than with that of generation f. 
According to Jurine, the antennae are true fins, the threads of 
which are spread out or united at the will of the animal, and in pro- 
portion to the degree of velocity it wishes to communicate to its 
motions; sometimes but a single one is visible, at others they are all 
displayed. We also think that these threads, and those of the two 
anterior feet, may be considered as aiding in respiration, quite as 
much as the laminae of the mandibles and of the two superior jaws, 
which M. Straus distinguishes by the name of branchial. The last, 
or those of the jaws, appear to me to be true but greatly dilated pal])!, 
and the two others are appendages of the mandibular palpi. Sec 
Jurine, Hist, des Mon. VI, 3. 
According to the naturalist of Geneva before mentioned, these 
animals, while they are swimming, move their anterior feet as ra- 
pidly as their antenna?, but very slowly when walking over the sur- 
face of aquatic plants. These feet, conjointly with the two terminated 
by a long hook, or the penultimates, then su])port the body. He suj)- 
l)oses that those which, according to him, form the second pair, are 
destined to create an aqueous curi’ent and to direct it toward the 
* In the figure given by Randohr these feet consist of hut three joints, and the 
last is somewhat dilated and cinarginatcd at the end, with a hook in the middle of 
the cmarginntion. 
I See the alimentary canal of the Daithniu index, figured by Jurine, X, 7, and 
Raiidohr, Monoc. Tab. V, ii, d, d, and x. 
