INFUSORIA PARASITIC IN CEPHALOPODA. 185 
The great scarcity of the parasites is remarkable. Out of 
309 cephalopods examined only eleven were infected—i. e. 
about 3°5 per cent. 
It is possible that the organisms occurring in different 
hosts are different species, but it seems to me unlikely. 
Assuming that there are but three species of Infusoria, their 
occurrence may be briefly summed up as follows: 
Parasites. Hosts. 
1. Opalinopsis sepiole . Sepiola rondeletii (liver). 
Octopus tetracirrhus 
(liver). 
Sepia officinalis (liver 
and kidneys). 
2. Chromidinaelegans . Sepiaelegans (kidneys). 
Illex coindetii (kidneys). 
Sepia orbignyana 
(kidneys). 
3. Chromidinacoronata . Octopus vulgaris 
(kidneys). 
Kledone aldrovandi 
(kidneys). 
Illex coindetii (kidneys). 
This table combines all the results of the work of 
Foettinger, Gonder, and myself as regards hosts. It may 
be noted that all the work on these organisms has been done 
upon material obtained from the Gulf of Naples. 
Chromidina elegans, Foett. emend. Gonder. 
The general morphology of this infusorian has been accu- 
rately described by Foettinger and Gonder. I will here 
record only those points in which my observations are in 
disagreement with those of these two investigators. 
A point which does not seem to have been noticed pre- 
viously is that the body is not uniform in shape throughout 
its whole length. Immediately behind the head there is a 
