156 MARIE V. LEBOUR. 
RHIZOPODA. 
Amoebze, as Lohmann has pointed out, are not uncommon in the 
plankton. He records two forms, the largest number being 75,000 in 100 
litres, but usually much less. He found July and August were the 
months in which they occur, and they were only found in depths of 
5S and 10m. I find them from May to October, the greatest number 
being 140 in a litre. However, I have seen them much commoner than 
this in surface samples in 1915 when they were not counted. They occur 
in the surface water and also from 5 and 7 fathoms, the greatest number 
being from the surface. They are to be found either by examining the 
water directly or keeping it for a day or two, and, I think, there is no 
doubt that they are really free-living and do not come from harbouring 
in other animals. Three forms occur, one very much more common 
than the others. I have designated them A, Band C. Bis very common, 
A and C only occurred once each. A prominent feature of all is the form 
of the pseudopodia, which are all spiky when fully outstretched and in the 
forms A and B give the animal the appearance of a heliozoon. However, 
they were constantly observed to retract and were in reality perfectly 
soft although apparently firm. 
Form A (Fig. 9, A, 1,2 and 3), a very minute species, pale greenish 
brown with very long and exceedingly slender spine-lke pseudopodia. 
Greenish and brown granules inside. Circular even when the pseudo- 
podia are retracted. 
Form B (Fig. 9, B, 1, 2 and 3). Very common, larger than A, hyaline 
and perfectly colourless. Perhaps this is the same species as Lohmann’s 
No. 2. The pseudopodia stick out in regular spikes, much shorter and 
thicker than in A. These move in various ways and can be completely 
retracted. May to October. Maximum in May. 
Form C (Fig. 9, C, 1,2 and 3). A very clear and also perfectly colour- 
less form with a conspicuous central nucleus. At one end only isa small 
frill of spiky pseudopodia. These are usually in the same position, but 
are capable of being changed and appearing in another place. 
All these Amoebe are entirely lost by the nets. 
Heliozoa indet. Rare, only in November. 
Foranunifera indet., including Polystomella sp., occurred fairly fre- 
quently in the tow nets, especially in winter when they were stirred up 
from the bottom. 
