266 
CRUSTACEA. 
by the muscles, and apparently acting in the manner of a cup or 
sucker. Those of the second pair are prehensile, the thighs large and 
spinous, and the tarsi composed of three joints, the last of which is 
provided with two hooks. The remaining feet are terminated by a 
fin formed of two elongated pinnulae, Avhose edges are fringed with 
bearded threads : the two first of the latter, or those of the third pair, 
including the four that precede them, have an additional but recurved 
toe. The two last are annexed to that portion of the body which 
projects posteriorly from the shell, or the tail. The female has but 
a single oviduct, covered by two small feet situated behind the two 
palettes. The organ which is considered as the penis of the male, 
is placed at the internal extremity of the preceding joint of the same 
feet near the origin of the two toes. On the same joint of the two 
preceding feet, and facing these organs of copulation, is a vesicle 
presumed to be seminal. The abdomen, by which we mean that part 
of the body which extends posteriorly from the ambulatory feet, the 
rostrum, and a tubercle containing the heart, is entirely free, without 
distinct articulations, and terminates directly after the last feet 
behind, by a sort of tail, in the form of a rounded lamina, deeply 
emarginated or bilobate, and without terminal hairs ; it is a species 
of fin. The body is so transparent that the heart may be distinguished 
through its parietes. It is situated behind the base of the siphon, 
lodged in a solid tubercle, semi-diaphanous and composed of a single 
ventricle. The blood, formed of little diaphanous globules, is 
impelled forwards in a column which soon divides into four branches, 
two of which proceed directly towards the eyes, and two towards the 
antennge; the latter are then reflected backwards and united to the 
former, constituting a single column on each side, which descends 
towards the cup, turns round its base, and disappears. A little beneath 
the two following feet, Ave may distinguish on each side another 
sanguineous column which curves outwards, extends along the 
borders of the shell, and having reached the two penultimate feet, is 
flexed forwards and ceases to be visible. Another, where, as in the 
preceding, the blood floAvs from the anterior part of the body to the 
posterior, and traverses longitudinally the middle of the tail ; it unites 
behind Avith tAvo other currents that may be seen on the edges of the 
tail, but Avhich floAV in a contrary direction, or appear to return the 
blood to the heart, Jurine avoids using the term A^essel, because the 
blood Avhich is driven into the anterior part of the body appears to 
be diffused there in such a manner as to induce us to believe that its 
globules, instead of being contained in particular vessels, are dispersed 
in the parenchyma of those parts. From Avhat avc have stated, how- 
ever, Avith respect to the circulation in the Decapoda, it is evident, 
that the blood, in the first instance, is distributed in the Arguli in the 
same Avay, and that the currents or columns of Avhich Ave have just 
spoken seem to indicate the existence of peculiar vessels. This able 
observer, in fact, subsequently acknowledges that the circulation is 
not every Avhere carried on in so diffused a manner as in the anterior 
part of the shell, Avhere, however, in our opinion, it is effectuated as 
in the Decapoda. The brain, Avhich is situated behind the eyes, 
appeared to him to be divided into three equal lobes, one anterior and 
