160 SCOLECOLBPIS FULIGINOSUS. 



Except that there is a diminution in the size of the feet posteriorly, the general 

 arrangement at the hundredth foot is similar. The dorsal bristles, however, are consider- 

 ably longer and more slender. The branchia remains fairly large, and some distance in 

 front of the tail is still conspicuous (Plate XCVII, fig. 3 c). The superior lamella has 

 become more convex and deeper, and the length of the slender dorsal bristles much 

 increased. The ventral hooks retain the same type as in front, and are accompanied by 

 the short bristles. Toward the tip of the tail (Plate XCVII, fig. 3 d) the branchise are 

 very short, indeed, in the last segments rudimentary. 



In life the lamellse of the feet as well as the branchise, which meet those of the 

 opposite side in front, are muscular, and undergo various movements. The ventral lobe 

 forms a flattened fan with a regular series of bristles in front. 



Reproduction.— On May 10th a female was laden with ova having the peculiar 

 spini-reticulate capsule (Plate XCIV, fig. 13), and some were not quite round. The 

 central region was pale and the contents granular. 



A young example, about \ of an inch in length, was found at St. Andrews in May 

 (R. Mcintosh). Such probably represents the growth of a year. 



Habits. — A dweller in sand, and an active and restless form. 



The Colobranchus tetracerus of Schmarda (1863) may be either this form or Scolecolepis 

 fuliginosus. 



It is probable that the Uncinia ciliata of De Quatrefages (1865) refers to this species, 

 and there is little in the description to separate it. The same may be said of Keferstein's 

 Colobranchus ciliatus. 



De St. Joseph (1894) described this as a new species (Nerine fiorseensis), basing the 

 distinction amongst other things on the tridentate crotchets which appear from the thirty- 

 second to the fifty-second segment, but in the ordinary form two spikes occur above the 

 main fang, and the figure l appears to have been drawn from a compressed or softened 

 example. The author regarded this form of hook as rare, but such is probably due to a 

 misapprehension. He states that the anus is surrounded by twenty to thirty cirri, and 

 that he has seen two of these longer, and occasionally bifurcate as an abnormality. He 

 identifies it with Malacocerus Girardi. A young example of 10 mm. had four eyes 

 arranged in a trapezoid and sixty-nine segments. 



Mesnil (1896), like De St. Joseph, could not satisfy himself as to the identity of 

 Johnston's Nerine vidgaris with De Quatrefages' Malacocerus vulgaris vel Scolecolepis 

 Girardi. He points out that what was sent from Heligoland as Nerine vulgaris, Johnston, 

 pertained to Scolecolepis fidiginosa, Claparede. Ehrenbaum considered Aonis Wagneri, 

 Leuckart, identical with the supposed Nerine vulgaris. He thought Colobranchus ciliatus, 

 Keferstein, a distinct form, a view not now held. 



2. Scolecolepis fuliginosus, Claparede, 1868. Plate XCVIII, figs. 4— 4 b— head, tail, etc.; 

 Plate XCVII, figs. 4—4 b— feet ; Plate CV, figs. 3—3 b— bristles and hook. 



Specific Characters. — Head in lateral view (in spirit) more pointed than that of 

 S. vulgaris, with a median cleft in front. Constriction behind the broad base of frontal 

 1 l Ann. Sc. nat./ ser. 7 e , t. xvii, PL IV, fig. 96. 



