SCOLECOLEPIS FITLIGINOSUS. 163 



and so with the superior lamella, which is narrower, with a rounded margin dorsally 

 and ventrally. The inter-lamellar notch is larger ; the ventral lamellar notch is narrower, 

 and the upper and lower margins slope evenly inward, so that the capstan-like outline is 

 lost. The superior bristles are still in two groups, and both occupy a considerable 

 distance of the margin. In the ventral division a few slender tapering bristles (pertaining 

 to the anterior row) occur superiorly and inferiorly, whilst the centre is occupied by 

 three hooks (posterior row). These (Plate OV, fig. 3 b) have a forward bend of the shaft, 

 and then a backward curve at the tip, which has well-marked wings. The tip has a 

 strong and not very acute main fang, and a single spine on the crown, and thus it 

 differs from that of S. vulgaris. A compressed foot viewed from the ventral surface is 

 shown in Plate XOVIII, fig. 4 b. Mesnil found the hooks appearing from the forty-second 

 to the forty-fifth foot on the French shores. Moreover, the shorter rows of bristles had 

 grains of yellowish-orange pigment on them. 



In the posterior feet (Plate XCVII, fig. 4 b) the branchia still retains a noteworthy 

 size, and the superior lamella shows a tendency to form a peak superiorly. The lower 

 lamella is almost on a level with the rounded margin of the region. The setigerons 

 process has a series of hooks with intermediate short bristles, besides a few above and 

 below. The hooks and bristles retain the same structure, though the latter are perhaps 

 more slender. 



Reproduction.— On July 19th the coelom of the females had many nearly ripe ovoid 

 ova with the peculiar capsule. 



Lo Bianco (1909) states that at Naples the period of sexual maturity is from October 

 to April. 



Claparede (1868) describes and figures the space in which the tentacular vessels are 

 held as filled with a mobile tissue in the form of a multitude of drops apparently sarcodic. 

 The segmental organs form a simple loop from the dissepiment to a point between the 

 feet. The general tissues of the animal have many bacilliparous follicles. 



Claparede and Mecznikow (1868) found ripe examples of this species at Naples 

 during the winter, the white sperms of the male issuing by the segmental pores, and 

 they describe the development of the egg from the early stages of its unequal segmenta- 

 tion to the escape of the trochophore with its two pigment spots (eyes) anteriorly, and 

 its tuft of cilia in front. The next stage presents the prototroch, mouth, and lateral 

 dimples of the body ; whilst, after eight days more, there are long, prominent bristles, 

 the regions of the alimentary canal, six eyes in a transverse row in front of the 

 prototroch, a telotroch, and four distinct segments of the body. 



Mesnil (1896), in his detailed account of this species, gives the number of the 

 dorsal and ventral hooks in the various segments, and other minute features. He also 

 (1896) makes two varieties of this form, viz. var. microchdeta from Naples, and macrocliseta 

 from the Channel, and of the latter two sub-divisions, minor and major, but such are 

 mainly of interest in demonstrating the variability of the species nnder diverse 

 conditions. 



A form which shows certain differences in the shape of the dorsal lamellee, and 

 which approaches Mesnil's S. Martinensis, comes from St. Andrews. The edge of the 

 dorsal lamella is more rounded. 



