48 Proceedings of the Royal Physical Society. 
Portobello, and visited the brickfield at the west end of the 
town; in one or two of the pools in the disused part of the 
brickfield, the same species was in great abundance, to the 
exclusion of almost every other form. During September 
1890, I made an examination of some shallow pools of water 
on May Island, when Cypris incongruens was observed to be 
moderately common, and this was the only fresh-water 
Ostracod I found on the island. I have now to notice a 
still more curious fact relating to the distribution of this 
species. In September 1887, my son, Mr Andrew Scott, 
who was, at that time, assistant chemist in the laboratory of 
the Baker Street Sugar Refinery, Greenock, belonging to 
Messrs Alexander Scott & Sons,—wrote me as follows oe 
“Twas up at one of the tanks on the roof of the sugar-house, 
and observed that the bottom was quite yellow. On closer 
examination the yellow substance turned out to be Ostra- 
coda—chiefly Cypris incongruens, there is also a Candona, 
I think” (this was Candona candida). “The tank was being 
cleaned out, so I took some of the mud, etc., for preservation. 
Now the curious thing is, how did the Ostracods get into the 
tank, seeing that any water that gathers is rain water, and 
the tank is cleaned out once a year?” 
Being desirous for further information about this matter, 
I wrote to the manager of the sugar-house, Mr Alexander 
S. MacLean (whom I have the privilege of counting as one of 
my friends), drawing his attention to the subject, and asking 
if he knew of any means by which the Ostracods could have - 
been introduced; and on 21st January 1888, he sent me the 
following interesting note :—“ Now as to the Ostracods, the 
tanks referred to consist of a set of three, measuring 40 feet ~ 
by 16 feet by 4 feet 6 inches deep, they are formed of cast- 
iron plates, and stand about 100 feet above the ground. One 
is covered with yellow pine boards, the other two are un- 
covered. They were wont to be supplied with water from 
Loch Thom, but the supply was shut off at the meter inlet 
four years ago when the tanks ceased to be used. Rain water 
collects in the two uncovered tanks, and that is the only 
water that has entered them since the Loch Thom water was 
shut off. I know, therefore, of no way by which these little 
animals could get in except by adhering to the claws of 
