114 F. W. GAMBLE, M.SC, AND J. H. ASHWOKTH, B.SC. 



males were comparatively rare in March and May of this year, when 

 mature females were abundant. In most cases the body-cavity was 

 full of spermatids in great bundles, as in Fig. 34. The ripe spermatozoa 

 closely resemble those of A. Grubii, which have been accurately figured 

 by Claparede. 1 They measure '058 mm. in length, and possess a 

 curiously shaped head, *004 mm. in length, and an extremely long 

 slender tail ("054 mm. long). The head (Figs. 28 and 29) is divisible 

 into three regions, — a rounded disc-like cap (S.) at the anterior end, 

 which is partially divided by a median groove ; the nucleus (iV.), which 

 is large and oval in shape; and the "middle piece" (M.), which bears 

 posteriorly a depression into which the tale is inserted. This depression 

 is formed only at the time when the spermatozoa are fully ripe. The 

 tail (T.) in the specimens which we have been able to obtain appeared 

 to be a somewhat stiff filament, which could only be bent to a com 

 paratively small extent. 



The breeding season of the "Laminarian" variety of Arenicola 

 marina lasts from February to May on the Lancashire coast. The large 

 black "worms" which may be dug out during the great spring tides 

 of these months are then distended with ova or spermatozoa. Males 

 and females are not distinguished by external characters, but owing to 

 the slight discharge of gonads from the nephridiopores consequent on 

 the tense condition of the body, it is often possible to distinguish the 

 sex of an example without dissection. It is at present impossible to 

 state how long these Arenicola live and how many times they breed. 



The ordiuary littoral lugworms of the Lancashire coast and of the 

 Isle of Man are not mature in the spring, and contain at most a few 

 very small eggs. In the summer (August) of 1896 we found mature 

 specimens, and we believe that this variety breeds through the summer, 

 commencing at about the time when the deeper water form has ceased. 



Relation of the Nephridia to the Reproductive System. — As is well 

 known, the ova and spermatazoa escape by the nephridiopores, but it 

 does not seem to have been noticed before, that in both males and 

 females the bladders of the last five pairs of nephridia are specially 

 enlarged (PL III., Fig. 15, Bl.), and contain mature ova or spermatozoa, 

 so that upon irritation a sinmltaneous discharge through all these 



1 ' Annelides de Naples,' 1868, pi. xix, fig. 2, C. 



