SEA-FISHERIES LABORATORY. 283 



(may be small). Five pairs of nephridia opening on seg- 

 ments 5 to 9. Twelve to twenty-eight pairs of gills. 

 Gonads small. 



Eecorded from the English Channel (Plymouth, the 

 Channel Islands and the French coast), Isle of Man, 

 Ireland (Valencia), Scotland (Loch Linnhe), the 

 Mediterranean. 



(b) A. ecaudata, Johnston.* — First gill on segment 

 16. Thirteen pairs of nephridia opening on segments 

 5 to IT. Nineteen to forty pairs of gills. Gonads large, 

 twelve pairs; in females each ovary bears as many as 

 thirty digitiform vascular processes bearing ova ; in 

 males each testis is produced into one or more large, thin 

 reniform lobes. 



Recorded from Scandinavia, the English Channel 

 (Plymouth, the Channel Islands and the French coast), 

 Isle of Man, Ireland (near Fairhead, Antrim). 



The Affinities of Ar en i col a mar i n a . 

 Arenicola marina is the only caudate species found in 

 Britain. As a comparison of the characters given above 

 shows, its nearest ally is the southern A. assimilis, var. 

 affinis, from which it differs in only two respects. In the 

 latter species there are several pairs of oesophageal glands 

 and no pouches on the first diaphragm, while in A. marina 

 there is a single pair of oesophageal glands and a pair of 

 septal pouches. The type specimens of A. assimilis are 

 rather further removed from A. marina, additional and 

 striking points of difference being found in the number of 

 chaetigerous segments (19 in A. marina, 20 in A. assimilis), 

 and the position of the first gill (on the seventh segment 

 in A. marina, on the eighth in A. assimilis). 



'■' For an account of this species see Gamble, F. W. and 

 Ashworth, J. H.— Q.J. M.S., Vol. 43, pp. 419-569. Pis. 22-29. 



