320 SERPULIDA. 
The anterior hooks are in groups of five or six, and-are long f-shaped structures which 
resemble somewhat those of Oligochets. The wide region or shoulder is in front of the 
middle (Plate CX XX, fig. 6a), the shaft tapering downward to the base, and upward to the 
long neck, which is almost straight. The main fang leaves the neck nearly at a right angle, 
is short and sharp, and on the crown above is a single prominent tooth. The whole organ 
thus characteristically differs from that of MZ. infundibulum. The posterior hooks (Plate 
CXXX, fig. 65) are minute, have a long, sharp main fang, and another above it almost as 
long, a nearly straight posterior outline, and a short base directed forward. The annelid 
secretes a transparent gelatinous tube in captivity and clings tenaciously to it. 
At least three species of Myzicola thus inhabit British waters, but in regard to the green 
example, it may be a question whether it is not a marked variety, with more transparent 
branchie of the type with the minute bifid anterior hooks. Fresh investigations are 
necessary. Only a single specimen has hitherto been obtained. 
Milne Edwards’ figure was copied by Chenu (1843-53). This figure is pale greenish 
throughout with seven dark spots along each branchial filament. In the dissection the 
nephridia hang out as long processes anteriorly. No distinct collar is shown, but apparently 
several folds occur in the region. Except for the collar-region it resembles a Sabellid of the 
ordinary type, with seven tufts of thoracic bristles. 
Milne Edwards! gave a drawing in which, besides the branchie, two pale tentacles on 
the mner side of the fan were shown. 
Famity XX XI.—SereuLips, Burmeister, Grube. 
Tubicola, Cuvier and Schweigger; Chetopodes tubicoles, Cuvier, ‘Régne Anim.,’ 1830; 
Anyulata cephalobranchia seu. tubicola, M. Kdwards; Capitibranchiata (sub-o.), Cirsted, 
1844, Siebold and Grube; Cephalobranchiata (nom. emend. quorund.). 
Cephalic lobe fused with the buccal segment, generally fascicles of bristles in the collar, 
which is open dorsally and fuses behind with the thoracic jacket ; mouth between two semi- 
circular, circular or spirally contorted laminze; cephalic region furnished with pinnate 
branchize, one or more (dorsal) of which terminates in an operculum or is specially modified 
into that structure. Branchial vessels simple. Body vermiform, of two regions ; segments 
short ; anterior segments fewer and thicker, ranging from three to nine, usually seven, and 
bearing fascicles of bristles dorsally, rows of hooks ventrally, the reverse arrangement occurring 
posteriorly ; collar fused with a thoracic cloak or jacket, which is open dorsally, the arrange- 
ment of which distinguishes the family from the Sabellids, and by some considered to be 
fused cirri; no copragogue ; dorsal and ventral surfaces ciliated at intervals; two glands 
anteriorly, with a common excretory duct ; glandular shields only in anterior region. Bristles 
various—massive with two short cones and a terminal whip, geniculate, with or without a 
gap at the tip, brush-like, capillary and bayonet-like. Hooks very thin, thus diverging 
from those of the Sabellids. Tube calcareous, more or less fixed to solid substances ; gre- 
garious. Cosmopolitan. 
In the 12th Edit. of the ‘Systema Natura of Linnzeus,’ annotated by his son, the descrip- 
tion of Serpula is “ animal Terebella. Testa univalvis, tubulosa adherens (seepe isthmus 
1 <Régne Anim., pl. la, fig. 2. 
at hy 
