SABELLA. 175 



Different species or varieties of the Sabella are found on the shores 

 and in the seas of Scotland. The most superficial observers must have 

 remarked agglomerated clusters of sandy tubes, with numerous circular 

 orifices, rudely resembling honeycomb ; or they may have seen flattened 

 tubes, composed more solidly of particles of sand agglutinated to the sur- 

 face of shells, in lines or curvatures over them. Or, it may be, they have 

 been struck with some single, perfect, conical tube of larger dimensions, 

 neatly constructed entirely of such particles, with or without a slight 

 silky lining, but altogether so fragile, as to be qualified to offer very little 

 resistance against violence. 



All these, whether weak or strong, solitary or conglomerated, con- 

 fined or capacious, are the work of their respective tenants, and occupied 

 by animals admitting of some comparision with the Nereis and Spio, but 

 of closer resemblances among themselves. 



The Sabella is occupied long and sedulously in fabricating its dwel- 

 ling, which, from the first, is never quitted, for it does not seem capable 

 of constructing a new one. 



1. SABELLA ALVEOLARIA The Honeycomb Sabella. Plate XXV. 



Figs. 1, 2, 3. 



The length of this diminutive architect is nine lines ; thickness above 

 one. Body round, composed of numerous segments, with bristles from 

 the side of some. A slender caudal appendage, generally folded up on 

 the body, terminates its extremity. The anterior extremity of the ani- 

 mal is cleft longitudinally, with two stout obtuse halves, each bordered 

 by about forty tentacular organs, being eighty in all, on a specimen. 

 These organs are extremely flexible, and apparently cartilaginous, under 

 the microscope. One surface has a groove in the centre, its remainder 

 comes out like a file, which peculiar conformation is more conspicuous 

 on the edges. But when completely extended, these organs are pectinate 

 on both sides, exactly in miniature like the weapon of the saw-fish, ex- 

 cept in colour, as may be discovered by microscopical observation. 



