200 TEREBELLA. 



tion between them, both in habits and configuration, be obvious, few 

 have attempted to correct the error. 



The largest specimens of the Shell-binder extend above five inches. 

 Pencils of several bristles and fleshy stumps down the sides, long flexible 

 tentacula, a mouth with active lips, resemble those of the others. The 

 posterior extremity is slightly trumpet-shaped. Plate XX VIII. fig. 4. 



The branchise consists of two bunches of ten or twelve beautiful 

 florid fleshy filaments in each/which resemble expanding ringlets, spirals, 

 or screws. Their incessant motion by contraction and dilatation, together 

 with the involution of the parts, renders it impracticable to discover du- 

 ring life, whether these bundles are collectively sustained each on a short 

 stem, both on one stem, or whether they originate from the skin. The}- 

 are confused, decayed, and disfigured in death. A very vivid crimson 

 spot marks the extremities, fig. 5. The body of the animal is also of a fine 

 red, probably speckled, because specks are exposed by fading of the deeper 

 hue, especially towards the lower extremity. About twenty-five tenta- 

 cula, infinitely stronger, and considerably longer than those of the Tcre- 

 bella littoralis, form the complement belonging to the present species ; 

 they are at least five times their diameter. They are nearly the length 

 of the body, and capable of laborious efforts. Flattening like a ribband, 

 they fold longitudinally in seizing an object. 



The fashion of the operation of the tentacula is according to the 

 service required. The portion applied to the smooth surfaces is flatten- 

 ed ; or the longitudinal fold, naturally preserved by the whole tenta- 

 culum, opens to seize and convey solid substances to whatever point is 

 required, fig. 6. Each portion of the tentaculum is endowed with a 

 prehensile faculty independently of every other portion, so that, if the 

 middle applies to any surface, or seizes any object, the remainder, both 

 behind and before, can fulfil similar functions at the same moment. A 

 number thus affixed by intermediate points in their length, resemble so 

 much extended cordages. A row of round red spots runs down the 

 middle of each, fig. 7. 



A strong musky odour exhales from some specimens of the Terc- 

 bella conchilega recovered from the deep sea. 



