SERPULA VERMICULARIS. 359 
thin, and the divisional striz run to the centre, cutting off the hypodermic areas. Moreover, 
though the surface of the cup appears smooth to the naked eye, it presents under the micro- 
Scope numerous minute chitinoid papillee, and if it has been injured, the cicatrix and various 
irregularities of the divisions are apparent. Occasionally abnormalities, not due to injury, 
are present. 
The body is, in the preparations, broad in front, and tapers gradually to the tail, which 
ends in the anus. It is flattened both dorsally and ventrally anteriorly, indeed more or less 
so throughout, and marked ventrally by a median groove, which commences behind a tri- 
angular area in front and extends to the posterior end. The anterior region consists of seven 
bristled segments and the fused peristomial segment, and it is proportionally shorter than 
in Hydroides. The alar membrane is broad dorsally, the sides touching in front and separating 
posteriorly, whilst the ventral lamella is of moderate breadth. The first pair of pale golden 
bristle-tufts is even more widely separated than in Hydroides, arising from prominent seti- 
gerous processes a little behind the anterior dorsal angle of the alar membrane and collar. 
The distance between this and the next tuft is nearly as large as between the second and 
seventh, and the direction is upward and forward. The bristles closely correspond in struc- 
ture with those of Hydroides norvegica, and their function is probably similar. Each tuft 
has a series of strong bristles with long, slightly curved shafts, which expand a little at the 
shoulder, though some also present a slight convexity posteriorly in the same region. Over 
the anterior edge of the shoulder are two short, conical spurs, whilst the posterior half is 
extended into a long tapering serrated process (Plate CXXX, fig. 10). As indicated by 
Fauvel, the region below these spurs is roughened by numerous spikes in young forms. They 
afterwards completely disappear. Interspersed with these are the long, simple tapering 
curved bristles, with minutely serrated edges as in Hydroiwdes. The other bristles of the 
region spring from shorter setigerous processes, have nearly straight shafts and shghtly 
curved tapering tips, with narrow serrated wings (Plate CXXX, fig. 10a).  Bristles are 
absent from a great part of the posterior region, again reappearing in groups toward the 
tail. They are very long, slender bristles, tapering to a hair-like point which is finely 
serrated (Plate CX XX, fig. 106). They are longest at the commencement of the series, 
diminish posteriorly, and are accompanied by short brush-shaped forms (Plate CX XX, fig. 10c), 
one outline of the dilated tip being longer than the other. The posterior bristles often have 
a peculiar fungoid (?) growth, which forms a blackish coating to the shaft or to 
the tip. 
The anterior hooks (Plate CXXXI, fig. 3) are avicular, with four teeth above the main 
fang, which has a well-marked gulf below and a prominent prow which projects about as 
far as the point of the chief fang. The crown is comparatively narrow, and the posterior 
outline is slightly concave, whilst the inferior edge is convex, with a shght incurvation 
posteriorly. The body of the hook is striated. 
The posterior hooks (Plate CXX XI, fig. 3a) are smaller, have as a rule five teeth above 
the main fang, the prow is less prominent, the inflection of the posterior outline is nearer 
the base, and the basal outline has a more distinct inflection posteriorly. Strize likewise 
pass from the teeth down the body of the hook. ‘The number of hooks in each row is large. 
Fauvel gives a total of six to eight teeth in the posterior hooks. 
The tube (Plate CXVI, figs. 4 and 4a), either fixed or free, is of a rosy or greenish colour, 
