NERINE FOLIOSA. 147 



The nephridia occur in the posterior region, and are described by Cunningham and 

 Eainage as spherical in shape, with short internal and external ducts. 



Reproduction. — Ova abound in examples towards the end of June and in July at 

 St. Andrews. 



Little change, to judge from Claparede and Mecznikow's larvse of Audouinia filigera, 1 

 occurs in the development of this form from the length of 1-3 mm. onwards. 



Alex. Agassiz (1866) clearly distinguished between the young of Nerine and that of 

 Polydora, and traced the growth of a Nerine which he linked to Nerine foliosa (his N. 

 coniocephala). His youngest stage had seven bristled segments, besides the bunch of 

 temporary bristles in front, which, as the author states, " spread fan-like in every direc- 

 tion, and the animals roll themselves up in a ball like a hedgehog, and become quite 

 motionless, but soon start off again on their rapid gyrations, performed by means of an 

 exceedingly powerful circle of vibratile cilia surrounding the head," and perhaps aided by 

 those on the tail. The body-segments have indications of dorsal cirri, with tw r o tufts of 

 bristles, the one serrated, file-like, the other smooth capillary forms. Six eye-like pigment- 

 specks occur on the head, the outer posterior on each side soon disappearing. The later 

 stages chiefly differ in the elongation of the body, the disappearance of the temporary 

 bristles, the occurrence of stiff hook-shaped bristles, the presence of rows of short cilia on 

 the segments dorsally and ventrally (younger stages), the increase of the dorsal cirri, and 

 the elongation of the tentacles. The alimentary canal is differentiated into gullet, stomach 

 and intestine. He points out that the serrated bristles are not lost, but form a long tuft 

 on the posterior side of the dorsal cirri. He thought Claparede was warranted in asso- 

 ciating the group (Nerine, Spio and Polydora) with the Aricise, and that the earlier stages 

 of Nerine resembled Busch's larva. 2 It is curious that in certain fossil annelids bunches 

 or single bristles — all large and rough — occur, and appear out of proportion to the width 

 of the body. 



Habits. — It is strictly a dweller in wet sand through which it evidently burrows with 

 ease, the powerful and prominent hooks posteriorly enabling it to cling firmly to its 

 tunnel. Though dug out almost entire it soon abbreviates itself, either in sea- water or in 

 a vasculum amidst seaweeds. The tentacles are often thrown off when immersed in spirit. 

 The thrusting out of the proboscis is less complex than in Magelona, for Nerine bores in 

 the sand with its pointed snout and muscular body. It gulps water by the mouth. It is 

 neutral to test-paper. 



A curious specimen comes from the West Sands, St. Andrews, March 26th, 1898, in 

 which the branchiee form simple subulate filaments along the dorsum, and the setigerous 

 processes for the dorsal bristles are rounded and almost conical. The specimen is much 

 softened, and the changes may have been partly due to maceration. The bristles and 

 hooks resemble those of Nerine foliosa. 



So far as can be ascertained, the Lumbricus squamatus of Abildgaard (1806) comes 

 nearest to this species both in description and figures — if by " squamis " lamellae are meant, 

 and the figures bear this out. The colours, structure and habits agree. 



The Spio Isemcomis of H. Rathke 3 (1837) seems to be a closely allied form. 



1 f Zeitschr. f. wiss. Zool./ Bd. xix, p. 193, Taf. xii, fig. 5. 



2 ( Beobachtungen/ pi. viii, fig. 1 — 2. 



3 ' Fauna der Krym/ p. 421, Tab. viii, fig. 1—6. 



