120 AMPHITRITE FIGULTIS. 



is the first small shield or scute. The first bristle-tuft is opposite the last branchia, only 

 a short interval separating it from the base of the organ. It springs from a setigerous 

 papilla at the dorsal edge of the ridge for the hooks. The bristles form a vertical row 

 of considerable depth, and in structure agree with the succeeding tufts, no rudimentary 

 forms marking the commencement of the series, as in various groups. Each tuft consists 

 of a longer series with stout, straight and long shafts, the free portion of which is slightly 

 diminished in diameter toward the commencement of the winged, finely tapered and 

 curved tip (Plate CXXV, figs. 10 and 10 a, and Plate CXXVa, fig. 1). The tips of 

 the bristles are directed upward and backward in their normal condition. The shorter 

 series consists of those with shorter and less tapered winged tips, which have an accessory 

 terminal blade carried at an angle to that beneath, and is broad at the base and tapered 

 to a slender, slightly curved tip. Such a bristle approaches that of certain Acoeticlse, 

 such as Panthalis. The structure of these bristles remains the same from the first tuft 

 to the last, but the setigerous processes increase in prominence in their progress backward. 

 The serratures at the tip cause them to cling tenaciously to the cuticle. 



No hooks or their homologues occur in the ridge running downward from the first 

 bristle-tuft and the ridge itself is intermediate in character. The ridge from the second 

 pair of bristles presents a lateral border and a median linear elevation containing the 

 single row of hooks, the ridge terminating ventrally in a rounded border at some distance 

 from the ventral shield) the ridges which follow gradually approach the ventral scutes 

 or shields until at the eighth they touch. The third ridge has a double row of hooks, 

 but they appear to be less regular than those which follow. As a rule the ridges 

 for the hooks are longest in front, and diminish a little toward the twenty-fourth 

 bristle-bundle. Bach leaves the setigerous process as a slightly flattened ridge with 

 an anterior, a median, and a posterior fillet, the median bearing the rows of hooks. 

 On the cessation of the bristles the thick and rather long ridge for the hooks increases 

 in prominence and presents a free edge dorsally and ventrally. It diminishes in 

 depth, while increasing in prominence posteriorly. The rows of hooks in life are 

 terminated ventrally by a browmish speck. In the posterior processes the hooks are 

 in a single row. 



The hooks, which commence at the second bristle-tuft and continue to the posterior 

 end (Plate CXXVa, fig. 1 a), differ from those of A. cirrata in the less oblique base and 

 in the curves of the anterior outline below the main fang. Usually four teeth occur in 

 lateral view on the crown above the fang, but when examined in front the crown appears 

 to have several transverse rows. These hooks are very similar to those of Amphitrite 

 variabilis, Risso, as figured by Marenzeller, but the latter has only seventeen pairs 

 of bristles. 



The ccelomic corpuscles immediately after extrusion in spirit are ovoid or elliptical 

 bodies, reddish in mass, the larger of a certain uniformity of size, filled with rather coarse 

 granules and with a nucleus. Amongst these are many smaller rounded bodies, some with 

 two large nuclei — it may be in process of fission — and, indeed, the process of division is seen 

 in others. The smallest are minute, translucent, elliptical bodies, though some are 

 fusiform with a nucleus in the centre, and a number may be strung together in a small 

 coagulum. From these the larger corpuscles seem to be developed, numerous divisions 



