9 
Mode of feeding. 
I have found no nutritive matter in the digestive cavity, but 
from the structure and position of the nutritive polyps we may 
draw some conclusions with regard to the mode of feeding of this 
animal. First of all, on account of the degenerate condition of the 
tentacles, the animal is absolutely incapable of catching food in the 
usual way. R. E. LI oyd (1907) has described a peculiar hydroid, 
Nudiclava monocanthi, epizoic on a pelagical fish, Monocanthus 
tomentosus. The hydranths are short, club-shaped, and devoid of 
tentacles; the endoderm is strongly developed with a powerful 
musculature. The author suggests that the closely packed hydranths 
open themselves like as many funnels, the widely gaping mouth 
openings directed forwards when the fish is swimming, thus re- 
ceiving tiny organisms from the plankton during the progression 
of the fish through the water. This may be true in the case in 
question, where the polyps are short and stout, but it does not 
hold good for Kinetocodium with its long and siender polyps. — Is 
it a commensal animal? Does it steal food from the pteropod? I 
think not, considering the mode of feeding of the pteropod and the 
position of the hydroid polyps around the opening of the shell, 
particularly on the front margin of the latter. The pteropod feeds 
on pelagical organisms which are carried forwards towards the 
mouth by means of the ciliary motion of the epithelium on the 
ventral surface of the hind part of the foot. In Hyalæa trispinosa 
this part of the foot is comparatively long. When the pteropod is 
expanded, it must be impossible or, in any case, most inconvenient 
for the polyps to reach the ciliated ventral surface of the foot or 
the mouth opening, which is protected in front by the confluent 
lateral lips. Thus our species seems to be unfit for any form of 
feeding on pelagical organisms. 
The strong development of the musculature in the mouth region 
lends the mouth the appearance of a sucking or biting organ. 
Moreover we must attend to the peculiar double bending of the 
pedicel. Finally the well-developed musculature of the pedicel renders 
the whole polyp very movable. 
I have thought of the possibility that the hydroid might seek 
its food on the shell of the pteropod. But what kind of food 
