420 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



FURTHER NOTE ON DECAPOD LARVAE IN THE 

 IRISH SEA. 



By H. Gr. Jackson, M.Sc. 



Introductory. 



The short report which follows is limited in 

 scope. It contains an account of the organisms 

 captured in the sea round the south end of 

 the Isle of Man by means of the large Nansen 

 and shear-nets (with two hauls of a " weight-net ") 

 used on the S.Y. " Runa," in April, 1913. These hauls 

 were made with the object rather of collecting considerable 

 quantities of the macro-plankton than for quantitative 

 estimation ; so, with the exception of the Decapod larvae, 

 only a qualitative survey has been attempted. As both 

 the large Nansen and the shear-net are of coarse-meshed 

 material comparatively few of the smaller organisms were 

 retained. The weight-net was an ordinary tow-net, 

 equipped with embroidery canvas instead of silk, which 

 was sunk by a heavy weight to a few feet from the sea- 

 bottom, and towed very slowly. It proved very efficient 

 for the capture of Crustacean larvae. The large Nansen 

 net (1 metre in diameter at mouth) was invariably used 

 as a surface tow-net in the customary fashion. The 

 shear-net (of embroidery canvas, mouth 1 metre square) 

 was, as usual, worked at an average depth of 10 fathoms. 

 The bottles here reported on contained, therefore, two 

 kinds of material ; a series of surface gatherings taken in 

 a large coarse net, and a series of gatherings also made 

 with coarse nets at depths from 8-12 fathoms. 



I may now give a few notes in regard to the smaller 

 organisms found associated with the Decapod larvae. 



