SERPULA VERMICULARIS. 353 
blade. Branchize of moderate length, the filaments tapering from base to apex, where 
there is a long process. Pinne of moderate length. Circular membrane at base. Operculum 
a fluted vase of 50—106 crenations and supported on a funnel-shaped pedicle—broad 
end upward. Rudimentary operculum a short clavate process. Body broad in front and 
gradually tapered to the anus. Ventral median groove from a triangular area in front 
to the tip of the tail. Anterior region of seven bristled segments, with short thoracic 
membrane. Posterior region of many segments (70—-140). First pair of bristle-tufts 
has long setigerous processes, with two kinds of bristles, viz., a strong series with a 
shoulder, two spurs, and a terminal whip, and a more slender series with curved, slightly 
tapered and serrated tips. The succeeding bristles of the region have tapering tips, with 
narrow serrated wings. Posterior bristles very long and slender, with a minutely serrated, 
hair-like point. Asymmetrical brush-shaped bristles accompany them. Anterior hooks 
avicular, with four teeth above the main fang and a prominent prow beneath it. Posterior 
hooks smaller, and with five teeth above the chief fang. Tube has a trumpet-shaped 
aperture, with rings of growth, spirally coiled posteriorly ; free or fixed. 
Philippi was inclined to restrict the genus Serpula to those having the operculum horny 
and in the form of a shallow funnel-shaped plate, supported on a subconical fleshy petiole ; 
but such a character, apart from the structure of the soft parts, bristles and hooks, is not 
rehable. 
1. SERPULA VERMICULARIS, Linneus (Lllis), 1755. Plate CXVI, figs. 4 and 4a—tubes ; 
Plate CXXI, figs. 7 and 7a—operculum and branchia; Plate CX XX, figs. 10—10c— 
bristles ; Plate CX X XI, figs. 3 and 3a—hooks. 
Specific Characters.—Collar with a considerable gap dorsally, passing as a deep frilled 
lamella laterally and continuous from side to side ventrally, Branchize of moderate length, 
with thick cuticle and of a bright red hue near the tip, the filaments diminishing from base 
to apex and ending in a long tapering process. Pinne of moderate length, longest about 
one-third from the tip, tapered from base to apex. Rudimentary operculum a short clavate 
process. Complete operculum a fluted vase of fifty to one hundred crenations supported on 
a pedicle, which increases in size in its progress upward. Body reddish or orange, broad in 
front and gradually tapered to the tail, with the anus at the tip; flattened both dorsally 
and ventrally, and marked ventrally by a median groove, which runs from a triangular area 
in front to the tip of the tail. Anterior region short, of seven bristled segments, and the 
fused peristomial segment, with an alar membrane. Posterior region of the body has 70— 
140 segments, 
The first pair of bristle-tufts has long setigerous processes, and generally resembles 
that of Hydroides norvegica in structure, viz., with two kinds of bristles, a strong series 
with a shoulder, two spurs and a terminal whip, and a more slender series with slightly 
curved, tapered and serrated tips, but the tufts are separated by a greater interval from the 
next, and they are nearer the mid-dorsal line. The rest of the anterior bristles are simple, 
with tapering tips and narrow, serrated wings. The posterior bristles are extremely long 
and slender, with a minutely serrated, hair-like point. Asymmetrical brush-shaped bristles 
accompany them. Anterior hooks in long rows, avicular, with four teeth above the main 
