CIRRATULUS CIRRATUS. 251 



greater. It is rounded dorsally, and somewhat flattened ventrally where a deep groove 

 runs from the first bristled segment backward to the tail. The body is slightly tapered 

 anteriorly, and more distinctly posteriorly where it ends in a point ventrally with the 

 anus above it, but in others the open vent posteriorly is simply crenate, probably from 

 dilatation. 



The colour varies from yellowish-orange to deep madder brown. Thus some are pink 

 or red in front, dull yellow mottled with brown or purple from the vessels along the body, 

 and dull yellow posteriorly. Others are deep madder brown throughout, relieved only 

 by the lighter cirri and the iridescent wrinkles of the surface. The tail is somewhat pale. 

 The cirri are not involved in this variation, being of the same yellow and red throughout. 



Two achastous segments follow the prostomium. The fourth segment has a smaller 

 sessile foot than the succeeding, bearing two minute tufts of bristles, which have the 

 structure of those of the previous species. It also carries a series of proportionally large 

 filiform branchial cirri arranged in two lateral tufts, each containing seven or eight 

 cirri, and of an orange colour, with red blood-vessels. These coil and twist during the 

 progress of the animal, and in proportion to the diameter of the body have a larger bulk 

 than those of C. tentaculatus. 



The following thirteen or fourteen segments bear branchial cirri, each arising above 

 and slightly behind a line through the middle of the bristle-tuft. Some of these show a 

 greater amount of blood than those in the dense anterior tufts. Here and there along 

 the body a single cirrus springs from the dorsal arch considerably above the bristles, 

 but the posterior region is devoid of them. On the whole the cirri are much fewer 

 than in G. tentaculatus, and do not show so conspicuously the remarkable spiral coils so 

 characteristic of that species. 



The feet differ from those of G. tentaculatus, in so far as they are more prominent, 

 and the superior and inferior divisions considerably closer, indeed in some, e. g. the first, 

 the bases inserted in the tissues closely approach. The first twelve bristled segments have 

 only the simple flattened, tapering bristles, the points being extremely slender (Plate 

 CVII, figs. 2 and 2 a). The ventral tufts are distinguished from the dorsal by their short- 

 ness and in some by their proportionally broader tips. The dorsal bristles slightly dilate 

 from the base nearly to the middle of the shaft, then taper gradually to the very fine 

 hair-like tip. Parasitic structures, such as algse, abound on them, and frequently they 

 render them pinnate besides winding round them. The edge of each bristle is minutely 

 and regularly spinous, the direction being distal. 



At the thirteenth foot a single crotchet appears in the ventral division. These hooks 

 (Plate CVII, figs. 2 b and 2 c) dilate a little from the base upward to rather above the middle, 

 where there is a slight forward curve, then a faint slope backward occurs, and again a 

 forward bend to form the hook at the tip. This projects through a neatly rounded 

 aperture of the cuticle, is moderately acute in the uninjured forms, and in some even more 

 curved at the tip than in the figure. In the sixteenth bristled foot three hooks are present 

 and four in the twentieth. A bristle or two accompany the hooks. 



The crotchets commence in the dorsal division about the thirtieth foot, a slender, 

 sharp-pointed one appearing in the twenty-ninth and perhaps earlier along with the 

 bristles. They continue to the posterior end, both divisions having a few slender tapering 



