44 SCLEROCHEILUS MINUTUS. 



less abraded. De St. Joseph associates these with the making of its galleries in the 

 shells, just as in the case of the powerful hooks on the fifth segment of Poly dor a. Their 

 function, whatever it may be, is certainly important, and they are moved by special 

 muscles. They are brownish by transmitted light, and have no longitudinal striae. 



The next and the succeeding segments have the simple curved bristles (Plate CIII, 

 fig. 8), of a fine pale-golden sheen, passing from the dorsal and ventral papillae, which 

 vary somewhat in appearance in the different parts of the body, forming shorter cones in 

 front, longer cones posteriorly. At the base of these bristles, and just projecting beyond 

 the skin in the preparations, are a series of bifid forms (Plate CIII, fig. 8 b) 9 one limb of 

 the fork being longer than the other, and the inner edge of both limbs is spinous. About 

 the twenty-second segment a slender cirrus, approaching a third the diameter of the body 

 at its longest, appears below the ventral papilla. According to De St. Joseph, its tip is 

 furnished with palpocils in life. 



This is a southern type so far as the present examples go, but it may yet occur on 

 the western shores. Its small size and obscure habits may have led to its being over- 

 looked, yet when captured the animal is lively, boring actively with its snout amongst 

 the mud. 



A post-larval Selerocheilus, measuring 4 or 5 mm. in length, was dredged in 1868 off 

 Sark by Col. the Hon. A. Fraser and Capt. Powell. Anteriorly are four black eyes, and 

 on each side of the broad anterior region are three of the strong hooked bristles 

 characteristic of the species. They point forward. 



The body, which at first sight resembled that of a young Spio, is widest at the end 

 of the anterior third, from which it is slightly tapered to the broad snout, while posteriorly 

 it gradually diminishes to the tail, which ends in two short processes and a cirrus, but the 

 former may be doubled cirri. The bristled segments appear to be between thirty and 

 forty. The second segment bearing the hooks has in addition several long, tapering, 

 slightly curved bristles (Plate XCVI, fig. 15). The succeeding segments have larger and 

 stronger tufts of these bristles (Plate CIII, fig. 8, and Plate C, fig. 3), which, though slightly 

 curved, stand stiffly out, so as to give the form a hirsute appearance. On the other hand, 

 the bristles of the posterior half slope backward in the preparation, though in life their 

 position might be as prominent as the foregoing. Moreover, at the base of each tuft are 

 minute bifid forms with unequal limbs to the fork (Plate CIII, fig. 86). This is probably 

 a young stage of the foregoing. 



Grube (1863), who discovered this form, apparently mistook the dorsal surface for the 

 ventral, and thus thought the ocular bands horny processes of the mouth. His description 

 is otherwise accurate. 



Selerocheilus was placed by De Quatrefages (1865) at the end of the Opheliidae of 

 uncertain position, for to him it had the appearance of an Ammotnjpane without branchiae, 

 and yet the large bristles of the second segment approached those of Polydora. 



A careful account was given in 1894 by De St. Joseph, who corrected Grube's 

 interpretation of the eyes as a horny band, and added considerably to our knowledge of its 

 structure and its relationships. He computed the segments at fifty-four or more, 

 described bacilliparus follicles in the hypoderm, and gave three rings to each segment. 



