198 PROF. W. A. HERDMAN ON THE DISTRIBUTION 
is 2571. Swarms of this oceanic species (fig. 18) in summer may possibly be 
connected with an inflow of Atlantie water ; bnt probably also large numbers 
appearing locally in enclosed areas may be the result of reproduction and 
development in situ. 
In some cases Acartia has been found in unusual abundance quite close to 
the shore, and even in water of low salinity. 
Towards the end of September, 1917, we emptied for cleaning purposes 
the large open-air fish-ponds at the Port Erin Biological Station, and when 
most of the water had been pumped out we noticed that what remained was 
swarming with small Copepoda. Every bucket and jarful that one removed 
for inspection was found to be densely crowded—as densely, in fact, as an 
average jar of plankton representing the contents of a standard haul. Some 
buckets of these Copepoda were used for feeding the lobster larvæ and 
some of the smaller fish and other animals in the Aquarium, and a small 
sample that was preserved was found to bea practically pure gathering of 
Acartia clausi. One specimen of Centropages was present in the tube amongst 
many thousands of Acartia, when Mr. Scott took the photo-micrograph shown 
in fig. 18. 
TEMORA. 
Temora longicornis (Müll.) is a very local species, which may be found on 
occasions swarming in great abundance in small areas of the sea, generally 
close to land. It is a summer species and its maximum is generally in June 
Fia. 19.— Temora longicornis from the stomach of a Mackerel. 
From a photo-micrograph by A. Scott. 
or July, but was in May in 1912, when the large hauls of 50,400 and 83,400 
were taken on the 17th and 20th respectively. Other large hauls of this 
