162 SCOLECOLBPIS FULIGINOSTTS. 



vulgaris, whilst from the dorsum a distinct median cleft occurs in front (Plate XCVIII, 

 fig. 4), and the tentacles (frontal " horns ") are longer than in the former species, a slight 

 crenation moreover appearing in the preparations on the anterior border between the 

 tentacle and the median furrow on each side. The constriction behind the broad base of 

 the frontal tentacles is marked in this species, and gives a character to the snout. The 

 tissues of the head generally are more translucent than in the common form. Behind 

 the frontal tentacles the head is produced into a triangle with the base in front, the 

 posterior peak ending in a ridge between the eyes without the special differentiation 

 characteristic of the previous species. The eyes form an elongated and somewhat kidney- 

 shaped mass on each side of this ridge with a smaller pair behind (Claparede and Mesnil). 



The long tentacles are absent in all the preparations, but probably they correspond 

 in structure with those of S. vulgaris. 



Mesnil observes that the French form has transverse black bands on the tentacles 

 (palpi), a cream-coloured touch appears laterally on the prostomium, and various touches 

 of black pigment occur on this region. 



The body is about 3 — 4 inches in length, smaller as a rule than S. vulgaris, from 

 which it is readily distinguished by the longer branchiae in the anterior region. It tapers 

 a little in front, but much more distinctly posteriorly, ending in a moderately attenuate tail 

 with the anus at the tip and surrounded by about eight flattened cirri, the two dorso-lateral 

 being more developed than the others (Mesnil) (Plate XCVIII, fig. 4 a). Segments about 

 160. The body is firm, somewhat flattened dorsally, and convex ventrally, where there 

 is a median band. Posteriorly it is more definitely flattened. The segments, though 

 numerous and narrow, are distinctly marked throughout. The mouth opens inferiorly a 

 short distance behind the tip of the snout, the lips, which slope from without backward 

 and inward, being marked by brown pigment. 



The first foot differs from that of S. vulgaris in carrying a proportionately larger 

 branchia, in the more acute tip of the narrower superior lamella, and in the narrower 

 and more prominent inferior lamella, which is somewhat truncated distally. The bristles, 

 both superiorly and inferiorly, are more delicate, but similarly arranged. 



The branchia increases in length to the tenth foot, where it forms a long, richly 

 ciliated process. The upper lamella is hatchet-shaped, viz. pointed and free superiorly 

 and with a rounded blunt border inferiorly, the notch between the two lamella being 

 distinct, with symmetrical sides. The inferior lamella is in outline capstan-shaped. 

 The long bristles at the upper edge of the dorsal tuft have very narrow wings (Plate CV, 

 fig. 3). The shorter forms dorsally and ventrally are finely tapered. 



At the twenty-fifth foot (Plate XCVII, fig. 4) the branchia is still large, though 

 after the fifteenth a slight decrease occurs (Mesnil), but there is no free process of the 

 diminished superior lamella, only a little conical projection marking its position. The 

 lamella approaches a semicircular outline with an abrupt margin inferiorly. The wings 

 on the long superior bristles are more distinct. The notch between the lamellse is still 

 wide, and the vertical diameter of the inferior lamella has increased, the outline, however, 

 remaining capstan-like. The shorter bristles, superiorly and inferiorly, are as figured. 

 A bristle with a hooked tip is shown in Plate CV, figs. 3 a. 



At the fiftieth foot (Plate XCVII, fig. 4 a) the diminution of the branchia is marked, 



