4S0 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



DECAPOD LARVAE IN THE IRISH SEA. 

 By H. G. Jackson, M.Sc 



I. Material Examined. 



This paper is a preliminary statement of the work 

 carried out on Decapod larvae in the L.M.B.C. district. 

 The material which has been investigated so far has been 

 obtained in the tow-nettings which were taken by 

 Prof. Herdman from his yacht " Ladybird " during 

 1907, along with those collected in Port Erin Bay during 

 those months of the year in which the yacht was not in 

 use. The similar nettings of years since 1907 have been 

 examined for supplementary evidence of the distribution 

 and occurrence of the larvae. Such larvae are rarely 

 present, in any but very small quantities, in the surface 

 tow-nets, so the deeper hauls of the shear-net have been 

 principally relied on for furnishing a reasonable indica- 

 tion of the young stages of Decapod larvae met with in 

 this portion of the Irish Sea. In consequence of this, 

 the records of the Bay hauls are unreliable and 

 fragmentary, and complete data are only obtainable for 

 the spring and autumn months — the periods in which the 

 yacht was at work. The gaps in these records are only 

 partially filled by the similar work carried on from the 

 Lancashire Sea Fisheries steamer, " James Fletcher," 

 owing to the fact that these latter investigations are 

 conducted in very different areas from those worked by 

 Prof. Herdman, so that, although use has been made of 

 this material, the data has not been included in the table 

 that follows : — 



