410 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



female fish is sometimes very great, and the extremes 

 often overlap with those of other species of fish, therefore 

 the identification of preserved material can only be 

 approximate. The eggs of some species of fish, which 

 are not recorded at all from the area although the adults 

 are known to occur, may, from overlapping in size, be 

 recorded along with the eggs of other species. The 

 number of eggs present in a single surface sample is 

 usually very small, and there is greater difficulty in 

 separating out the various kinds than when large numbers 

 can be dealt with. The identification of preserved 

 specimens of young fish in their larval and post-larval 

 condition is often almost impossible owing to the 

 mutilation that takes place when they are captured, and 

 any colour that may be present generally disappears in 

 the preservative. After the post-larval stage is reached 

 identification becomes more simple, but the young fish 

 sink deeper down in the water and are not often captured 

 by the ordinary surface nets. Young fishes, with the 

 exception of rockling (or mackerel midges) and sprats, 

 are seldom taken at the surface. 



The arrangement of the fishes followed here is that 

 adopted by G. A. Boulenger in the Cambridge Natural 

 History, Volume VII. 



Clwpea sprattus, Linn. — Sprat. 



The spawning period of the sprat, according to the 

 records made during the six years' intensive study of the 

 plankton collected at the south-west of the Isle of 

 Man, extends from the beginning of April to well into 

 September. In 1907 and 1908 the egg was only observed 

 in one collection in each of these years, viz., April 2nd, 

 1907, and April 27th, 1908. Its first appearance in 1909 

 was on May 3rd. It occurred frequently throughout that 



