Gattjj Marine Laboralori/j St. Andrews. 257 



relationship? of A'", lonjisetosa are doubtful — indeed, in all 

 ]n-obability it may refer to the long--bri.stled foi'ui of Sf. cieGcc. 

 The dredgings of the 'Porcupine' and 'Knight Errant,' of 

 Dr. Gwyn Jeffreys in Shetland, those of Canon ISToruiaii in 

 the same region and in Norway, and of the Royal Irish 

 Academy under Prof. Haddon and Dr. ScharfF, have consider- 

 ably extended the species, so t!iat there are at least double, 

 and perhaps treble, the number now known as British. 



The characters by which the species of Nephthys are distin- 

 guished from each other are less evident than in many otlier 

 families of Polycha^ta, and the observer is at first dissatisfied, 

 especially in regard to the structure of the bristles, with the 

 essential features diagnostic of each. A careful consideration 

 of the form of the head, the structure of the feet, and the 

 bristles, which are borne on the anterior fiice of each foot, with 

 other features, however, shows that, so far as known, the 

 distinctions are reliable, though it must be remembered that 

 further information in regard to sexual variation is needed. 



Accordingly the following nine species are found to be 

 natives of Britain : — 



The most abundant as well as the largest form is N'ephlhjs 

 cceca^ Fiibr., in which the wedge-shaped head is roundjd in 

 front, with two sensory papillai posteriorly. The body is 

 moderately elongate and of considerable thickness. Poste- 

 riorly it terminates in an anus with a median tapering cirrus 

 ventrally. The proboscis has twenty-two rows of papilhe, 

 five (or occasionally six) being in each row. The dorsal 

 lamella of the foot is fan- shaped and prominent, its deepest 

 part being external; dorsal cirrus short and tapering; bran- 

 chial process of considerable length, coiled externally, and 

 with a semicircular flap of the spinigerous lobe at its base 

 anteriorly. The ventral division of the foot has a large, 

 broadly lanceolate, and pointed lamella continuous witli the 

 fleshy lobes of the region. The ventral cirrus is of moderate 

 size, slightly flattened and conical. In front of the dorsal 

 lamella is a row of pale, elongate, serrate bristles which ex- 

 tend outwards fully three times the diameter of the lamella. 

 The serrated edge, forming a simple saw-like arrangement in 

 lateral view,. is reall}^ composed of a close series of transverse 

 spikes in each division. The bristle extends distally as an 

 extremely attenuate process, and tapers to a fine point devoid 

 of serrations. A narrow fleshy ridge, with the tip of the spine 

 projecting externally, comes next the foregoing bristles, and 

 then a series of the pale barred or camerated bristles in front. 

 No free flap guarding these bristles in front is present in this 



Ann. & Mag. N. tlist. Ser. 7. Vol. v. 17 



