Dr. H. Fol on the Family Tintinnodea. 79 
within and in part outside of the palettes; the palette being 
placed on the summit of the edge of the peristome, the cilia 
are implanted running downwards from it. ‘Those which are 
outside the peristome are generally strong and nearly as long 
as the palettes. I have never found more than a single circlet 
of cilia in this position ; it is this that Hickel has represented 
in his Codonella (tig. 8), but giving them an exaggerated 
length. According to Sterki (XI.) the freshwater Tintinnus 
semiciliatus has several circlets of cilia in this position, de- 
scending pretty low down upon the sides of the body. The 
cilia placed in the interior of the peristome are short and 
thick, becoming shorter as they approach the middle of the 
disk. 
I have been unable to discover, in any of the species that I 
have observed, the coating of fine cilia which, according to 
Claparéde and Lachmann and Hickel, covers the outer surface 
of the body in certain species. I believe I have met with the 
same two species to which the latter ascribes these cilia in his 
text and in his figures; and I have ascertained that these cilia 
do not exist. 
On the other hand, in some species I have met with a struc- 
ture which I have not satisfactorily succeeded in rendering 
evident. This is a membrane which proceeds from the body 
of the animal, being inserted a little below the peristome, and 
passing thence to the test, to which it is attached along a cir- 
cular line which occupies about the upper third of the latter. 
I only infer the existence of this membrane from some images 
furnished by animals treated with reagents, and in which, 
moreover, this structure is but rarely preserved; I possess 
only a single observation made during life, namely upon Co- 
donella galea. However, I must add that the images did not 
appear to me sufficiently clear to be definitely established, and 
it is a point that I only mention to call the attention of inves- 
tigators to it. It seemed to me that this membrane is suffi- 
ciently ample to permit the complete extension of the animal, 
and that in the retracted state of the latter it folds in the 
manner of an Indian-rubber tobacco-pouch, thus completely 
closing the access to the inner part of the test (see Pl. IV. 
fig. 14). 
In Codonella ventricosa (PI. IV. fig. 12) the free margin 
of the test is produced into a flexible membranous portion, 
which opens, in the state of extension, after the fashion of a 
straight neck, whilst it closes completely when the animal 
withdraws itself to dhe bottom of its test, forming a diaphragm 
over the orifice of the latter. The mechanism by which the 
animal in retracting itself produces this occlusion can only 
