DR. W. BAIED OSr NEW TUBICOLOUS ANNELIDS. 157 



On new Tubicolous Annelids, in the Collection of the British 



Museum. Part 2. By W. Baibd, M.D., P.L.S. 



[Read December 1, 1864.] 



[Plate V.] 



Grenus Teeebella, Linn. {Montagu). 



1. Terebella flabellum, Baird. PI. V. figs. 1 & 2. 



The animal is as yet unknown, but the tubes are sufficiently re- 

 markable to merit a description. The specimens, which have been 

 deposited in the collection of the British Museum, vary in size, 

 the largest being about 6 inches in length, and a.bout the circum- 

 ference of an ordinary goose-quill. They are cylindrical in form, 

 tapering gradually from the summit to the base; the upper 

 portion being the narrower. They are composed of a thin mem- 

 branous substance internally, covered externally with numerous 

 fragments of shells, corals, and pieces of horny zoophytes. The 

 most characteristic feature, however, in the structure of this tube 

 is the fan-shaped expansion of filaments at its upper orifice. This 

 orifice is circular, and has on its dorsal surface a projecting lip or 

 kind of hood (fig. 2), which extends beyond the mouth for a short 

 distance, whilst from its ventral side springs another lip or hood 

 (fig. 1), which quickly expands into a fan-shaped tuft of horny- 

 looking filaments. This tuft is composed of several branches, each 

 of which divides dichotomously into stiff but somewhat flexible 

 filaments, spreading out horizontally to the length of an inch or 

 more. These filaments are nodulous, and seem to possess a glu- 

 tinous secretion, by means of which they are able to attach small 

 shells, &c. to their surface. 



Hah. These tubes, to the number of six, were collected during 

 Sir J. Clarke B-oss's Antarctic Expedition — two of them being re- 

 gistered in our collection as from Narcon Island. (Mus. Brit.) 



2. Terebella bilineata, Baird. PI. V. figs. 3 &4. 

 Animal with three pairs of branchiae, composed of simple cirri- 

 form filaments (fig. 3). They are not arborescent, having no trunk 

 or main branch from which the others spring, but are inserted in 

 tufts of single filaments on the three first segments of the body, 

 on each side. The tentacula are composed of numerous, rather 

 long filaments, hollowed in the centre, and waved or undu- 

 lated along the edge. In the specimens we have preserved in 

 the collection, most of these have unfortunately fallen off. The 

 bristle tufts are continued to the end of the body, and are about 

 36 in number. The segments of the body are rather deeply 



