232 
ALFRED GIARD, 
individuals^ by cellular elements, which give rise to the 
genital products. I am at a loss to understand why 
Metschnikolf refuses the name of endoderm to a cell-layer 
which arises absolutely in the same way and plays precisely 
the same part as the part called by this name by all embryo- 
logists in the other Metazoa. 
I have seen in some Rhopalurse a cloud of agile corpuscles 
issue from the sides of the body between the third and the 
fourth metameres. Are these corpuscles spermatozoa ? It 
was not possible for me to get a distinct notion of their 
form, and I also am unable to affirm the presence of a natural 
opening at this spot on the body. It is possible that the 
specimens which presented this appearance of an emission of 
spermatozoa were really the victims of lacerations. 
IV. — Anatomy of Intoshia gigas. 
The second species of Orthonectida parasitic in Ophiocoma 
negiecta is much larger than Rhophalura. Its length is, in 
fact, two and a half times that of the latter. I name it 
Intoshia gigas. 
Intoshia presents in swimming alternative movements of 
contraction and expansion in a transverse direction. It does 
not possess a papilliferous ring, but simply a ring devoid of 
cilia in its place. The body is of a more regular breadth 
and less tapering at the two extremities, which are blunt 
points, a little more conical than in the Intoshia parasitic in 
Nemerteans and Planarians. 
Further, the anterior part of the body is strongly flattened 
in Intoshia gigas, and the non-ciliated segment presents on 
its inferior face, throughout its breadth, a transverse groove 
of some depth, so that the profile of the animal is that of a 
shoe with a heel to it (Plate XXII, fig. 5). 
The metamerisation is less distinct than in Rhopalura. 
After the cephalic ring and a cervical ring corresponding to 
the papilliferous ring there follow three metameres of de- 
creasing breadth (the third ( 7 ) is about half of the first (a), 
the second (j3) being of intermediate dimensions). To these 
follows a ring (S) of much larger size, which seems some- 
times to be divided into three, then follow two very small 
metameres (e and ?), which have about the same length as 7 , 
and, finally, the terminal piece. 
The variable dimensions of these metameres is no longer 
related, as in Rhopalura, to the size of the compound 
cells. 
Each metamere is, in fact, formed by several rows of cells, 
the cells of each row being regularly placed over the corre- 
