148 CRUSTACEA. 



composed of a single ventricle. The blood, formed of little diapha- 

 nous 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 antennae; the latter are then reflected back- 

 wards 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, we 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 flows from the ante- 

 rior part of the body to the posterior, traverses longitudinally the 

 middle of the tail; it unites behind with two other currents that may 

 be seen on the edges of the tail, but which flow in a contrary direc- 

 tion, or appear to return the blood to the heart. Jurine avoids using 

 the term vessel, because the blood which 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 what we have stated, however, with 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 way, and that the currents or 

 columns of which we have just spoken, seem to indicate the exis- 

 tence of peculiar vessels. This able observer, in fact, subsequently 

 acknowledges that the circulation is not every where carried on in 

 so diffused a manner as in the anterior part of the shell, where, how- 

 ever, in our opinion, it is effectuated as in the Decapoda. The brain, 

 which is situated behind the eyes, appeared to him to be divided into 

 three equal lobes, one anterior and two lateral. The anterior part 

 of the stomach gives origin to two large appendages, each divided 

 into two branches, which ramify in the wings of the shell. The 

 brownish coloured aliment they contain renders these ramifications 

 visible. The caecum is provided near its origin with two vermiform 

 appendages. 



The excessive ardour of the males frequently induces them to 

 mistake one sex for the other, or to make their advances to preg- 

 nant or dead females. They are placed in coition on their back, to 

 which they cling by means of their feet with cups, for several hours. 

 The period of gestation is from thirteen to nineteen days. The ova 

 are smooth, oval and milk-white. They are fixed with gluten on 

 stones or other indurated bodies, either in a straight line or in two 

 ranges, and from one to four hundred in number; being pressed 

 against each other, their form becomes almost hexagonal. 



Twenty-ive days after the extrusion of the ova, and after they 



