203 
(may be small). Five pairs of nephridia opening on seg- 
ments 5 to 9. Twelve to twenty-eight pairs of gills. 
Gonads small. 
Recorded from the English Channel (Plymouth, the 
Channel Islands and the French coast), Isle of Man, 
Iveland (Valencia), Scotland (Loch LTinnhe), the 
Mediterranean. 
(b) A. ecaudata, Johuston.*— First gill on segment 
LG. Thirteen pairs of nephridia opening on segments 
5tol7. Nineteen to forty pais of gills. Gonads large, 
twelve pairs; im 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 Arenicola marina. 
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. ass¢milis, var. 
affincs, from which it differs in only two respects. In the 
latter species there are several pairs of cesophageal glands 
and no pouches on the first diaphragm, while in A. marina 
there is a single pair of wsophageal glands and a pair of 
septal pouches. The type specimens of A. assemilis are 
rather further removed from A. marina, additional and 
striking points of difference being found in the number of 
chetigerous 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 these species see Gamble, F. W. and 
Ashworth, J. H.—Q.J.M.S., Vol. 43, pp. 419-569. Pls. 22-29. 
