TEREBELLIDES STROEML 209 



the latter has no eye-specks, and only two pairs of branchiae, whilst the nephridia occur 

 in the third, fourth, fifth and sixth segments. 



Malmgren instituted the sub-family Canephoridea for Terebellides, in which a single 

 quadripartite branchia occurs. The hooks are rostrate in the anterior region, pectiniform 

 in the posterior region. 



Genus CXL. — Terebellides, Sars, 1835. 



Cephalic lobe rounded-ovate, the plate being deeply frilled, and having a long and 

 smooth dorsal surface arising from a groove marking it from the first segment, and 

 ventrally being continuous so as to surround the mouth. The surface is covered by a 

 dense series of grooved tentacles. It is fused with the buccal segment. 1 Under the 

 mouth is a large bilobed plate. Body enlarged anteriorly, tapering gently backward and 

 terminating in a moderately slender tail with the crenate anus at the tip. Dorsal surface 

 smoothly rounded ; ventral surface is less rounded and posteriorly is flattened. Behind 

 the mouth and the cephalic plate which bounds it is a large semicircular flap or lamella 

 passing from side to side. Five distinct glandular belts on the ventral surface anteriorly, 

 and a belt in the line of the setigerous and uncinigerous processes. Branchiae arising 

 from a single powerful stem on the second and third segments, and having four divisions- 

 two larger dorsal and two smaller ventral. Each has a smooth basal process or arm above 

 which are a dense series of lamellae, which in the case of the dorsal project forward in 

 front of the basal stem. Gizzard present; glandular stomach, muscular and folded. 

 Setigerous processes eighteen pairs, commencing on the second segment (third, Hessle). 

 Bristles simple, long, tapering and winged. Hooks on slight lateral ridges in the 

 bristled region (from segment 7 ; 8, Hessle), and with long curved shafts (rostrate) ; 

 thereafter pectiniform on uncinigerous lamellae, and minute, the outline short and broad 

 with two or more teeth above the main fang. Anterior nephridia with long and well- 

 developed tubes, the posterior are small. They occur in the third, sixth and seventh 

 segments. Tubicolar in mud or muddy sand. 



1. Terebellides Strcemi, Sars, 1835. Plate CXX, fig. 3— body ; Plate CXXVII, 



figs. 5 — 5 b — bristles and hooks. 



Specific Characters. — Frilled cephalic plate elevated above the dorsal outline, and 

 the margins meet in the middle line ventrally to form a spout-shaped channel behind the 

 mouth. Cephalic plate directed anteriorly and posteriorly instead of dorsally and 

 ventrally as in Polycirrus and other forms. The posterior edges of the plate give origin 

 to the tentacles, which are of a pale flesh colour and often spatulate. Body 60 mm. long, 

 enlarged in front and gently tapered to the tail, which is by no means slender. Segments 

 fifty to fifty-six, of which eighteen are anterior. Ventral surface with bold glandular belts 

 (Hessle). Third, fourth and fifth segments have ventrally free anterior borders. The 



1 Coalesced (Grube). 



196 



