648 C. H. MARTIN. 
nematocysts have never been found in the other species of 
Ophryodendron which live upon Crustacea. 
The case of the nematocysts of Ophryodendron is, of 
course, paralleled by that of the nematocysts of Aolids, as 
has been shown by Grosvenor, and by that of the nemato- 
eysts of Turbellaria. I have had an opportunity of observing 
two analogous cases amongst Infusoria :— 
(1.) In some Kerona which were found on a rather morbid 
Hydra at Glasgow, the three characteristic Hydra nemato- 
cysts were present. 
(2.) During a stay at Naples I found that a holotrichous 
infusorian on Kudendrium, which seemed to agree in all 
essentials with the Holostoma described by Entz (loc. cit.), 
was full of the two very characteristic nematocysts of the 
hydroid in an unexploded condition. 
It is far more difficult to arrive at a clear conception of the 
process of feeding by direct observation in the case of the 
vermiform individual. During life the vermiform individual 
is in constant swaying motion on its stalk, touching with 
its anterior extremity all objects within reach. That the 
anterior end of. the vermiform individual possesses con- 
siderable power of suction is shown by the fact that an 
external vermiform bud which has not yet become completely 
detached from the parent proboscidiform individual, can often 
be seen applying its anterior end to the stalk of the hydroid, 
and pulling its parent right over. At the same time, nemato- 
cysts are always found in the vermiform individual, and in 
fixed preparations I have found cases in which a vermiform 
individual had its anterior end closely applied to the ecto- 
derm of a hydroid, whilst the nuclei of freshly ingested 
ectodermal cells were to be seen in its cytoplasm. 
7. Tae Exrernat Bupping or OpHRYODENDRON. 
In following the external budding of Ophryodendron on 
the living animal, as far as my experience goes it is essential 
that the Ophryodendron should be kept in a fairly deep 
