3J84 Dr GDldstream on the Structure and 



segments of the tail. There are three pairs of an irregularly 

 oval form (Fig. 14), and three pairs nearly quadrangular (Fig. 

 15), both sets being edged with long and pinnated bristles. 

 The oval ones are marked with lines radiating from their centres, 

 and, between these, there are seen numerous spherical bodies 

 (see Fig. 14.) These branchae are arranged in three rows, in 

 an imbricated manner, one of each kind being articulated toge- 

 ther on a common peduncle on either side ; (see Fig. 13, which 

 represents one of the caudal segments, with two pairs of the 

 branchial lamellae hanging from it.) The oval ones are situated 

 externally with regard to the others. The branchial scales 

 have no general covering, such as exists in several other animals 

 of the same class. 



I shall allude here to an organ situated within the cavity of 

 the tail, behind the branchiae, the function of which I am igno- 

 rant of. It consists of two vesicular bodies, of an oval form, 

 attached to a common peduncle (see Fig. 16.) I have always 

 seen these bodies filled with numerous minute, dark-coloured 

 granules, of an irregularly round shape, which could not be de- 

 tached from the substance in which they were imbedded, by 

 tearing it up. They exist in both males and females. 



The chief facts relating to the reproductive system which 

 have been well ascertained, are, \st, That the ova, during at 

 least a certain period of their existence, swim in a fluid contained 

 in the general cavity of the body, (perhaps enclosed within thin 

 sacs, lying along either side of the cavity, throughout its whole 

 length, and forming ovaries) ; and, 9.dly, that the female carries 

 its young in a pouch formed of scales, pendant from the third, 

 fourth, fifth, and sixth segments. With regard to the first fact, 

 it may be doubted whether the bodies alluded to as being dif- 

 fused through the abdominal cavity, be truly ova ; but it is dif- 

 ficult to conjecture what else they can be. In some individuals, 

 when a wound is made in the ligament connecting any two of 

 the segments, a gush of fluid instantly takes place ; and on exa- 

 mining this with the microscope, there are seen in it innumerable 

 transparent spherical bodies, varying from jjo^^ to ^oVu^^ ^^ 

 an inch in diameter. No trace of internal organization is dis- 

 coverable in these. The small globules exactly resemble the 

 larger ones in every thing except size. They remind me of 



