MARINE BIOLOGICAL STATION AT PORT ERIN. 85 
scantily represented; although neither species is ever 
absent for long, and occasional larger numbers occur— 
such as September 19th, off Calf Island, deep net, Podon 
70 and Hvadne 100, and September 20th, Station I, shear 
net, Podon 110 and 290, deep net 140, and, at the same 
time, inside the bay, 182. On September 23rd the 
ordinary surface net inside the bay took 550 Podon, and 
the following day 100, after which the numbers fall off 
rapidly. 
The common species of Ockoplewra that occurs in our 
district (O. dzoica) is also a form which seems to deserve 
special notice. It occurs throughout the year, being 
present in every month, and represented in nearly everv 
gathering. It is absent or rare in the case of the hauls 
taken on a few dates between August 24th and 28th, and 
then again on September 4th and 5th. With those 
exceptions, Ovkopleura is one of the most constant of 
organisms at all times of the year, and, moreover, 18 
usually present in quantities that range within narrow 
hmits, so that it does not vary to the extent that some 
Copepoda and Diatoms do. In the winter months— 
December, January, February and March—the numbers 
taken are low, but from April to November inclusive 
quantities of a thousand or two per net are very frequently 
taken. The highest numbers occur in April, and they 
only reach 5,500 per net, so there 1s no marked maximum. 
In some cases the numbers of Oitkopleura remain 
remarkably constant for several hauls, indicating a very 
general distribution through the water. For example, in 
one traverse of Port Erin Bay 2,780 were caught, and in 
the return traverse 2,030; then again, two adjacent hauls 
gave 3,540 and 3,600 respectively, and another pair of 
simultaneous hauls gave 2,250 each. But on the other 
hand, on another occasion, two successive traverses of the 
