(Jiiltif Miin'iK- Lahoralorij^ SL Awircioi. 2-37 



iThitioiisIiips of N. loiujisnlosii are diMibttul — iiiilecil, in all 

 ])riil)ability it may refer to tlie lon;^-bri.4tlecl funn of ^.V. C'vcu. 

 riic (lrcil<^in;^3 of the 'Porcupine' and ' Kniglit JOrrant,' of 

 Dr. Gwyn JefVreys in Slietlaiul, those of Canon Noniiaii in 

 the same religion ami in Norway, and of the Royal Irish 

 Academy under Prof, llaildon and Dr. Scharff, have consider- 

 ably extendrd the species, so t!iat there are at least douljle, 

 and j)erhaps treble, the number now known as British. 



Tlic characters by which the S|)ccies of Xejiht/ii/s aro distin- 

 guished from each other are less evident than in many other 

 families of Polycha>ta, and the observer is at Hrst 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 Nej>hlhys 

 ccvca, Fiibr., in which the wedge-shaped head is roundel in 

 front, with two sensory i)apillc^ j)osteriorly. The body is 

 moderately elongate and of considerable thickness. Poste- 

 riorly it terminates in an anus with a median tapering cirrus 

 ventrally. The jnoboscis has twenty-two rows of papilhc, 

 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 with 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 j)ale, elongate, serrate bristles which ex- 

 tend outwards fully three times the diameter of tiie lamella. 

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

 lateral view, is really composed of a close series of transverse 

 sj)ikc8 in each division. The bristle extends distally as an 

 extremely attenuate process, and tapers to a tine point devoid 

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

 projecting externally, comes next the foregoing bristles, and 

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

 -No free Hap guarding these bristles in front is [)resent in this 



Ann. cO Miuj. X. I/ist. Ser. 7. ]'ol. v. 17 



