SABELLA. 179 



to the latter, and whereon the institution of such a genus would be spe- 

 cially founded. 



Taking a great and comprehensive view of the general features of the 

 animated universe, many analogies in structure and habits will be found 

 in animals which now stand far apart, or are totally detached by artifi- 

 cial systems. In fact, our attention is to be here directed to individual 

 properties, leaving the strict associations of species in genera to future 

 labourers. 



The Sabella belgica or A mphitrite auricoma extends to four inches and 

 a half in length, by about three quarters of an inch at the shoulder ; and 

 the tube in which such a specimen dwelt was a hollow conic frustrura, 

 five inches long, tapering regularly downwards. 



Never having possessed a specimen in its highest vigour, I can only 

 say, that in general structure and in habits, it admits of comparison to 

 the Tcrebclla arenaria in many points. 



The anterior portion is distinguished by a flattened face, wherein the 

 mouth is situated ; two pair of flattened gills or branchiae appear on each 

 side of the head, with numerous tentacular organs, not extending far. Two 

 gilded fans, somewhat like a comb, rise from the head, consisting of eleven 

 or twelve short teeth. The head is presented as a spherical segment at the 

 orifice of the tube. It issues from a frill of four segments, more distinct 

 than any others, with pencils or bristles from their sides. Other fourteen, 

 also with pencils, compose the rest of the body, which terminates by a 

 large scoop, exhibiting rudimental segments indenting the back. The 

 general hue of the animal is reddish, the branchiae bright vermilion, and 

 a vivid red vessel traverses the body. 



This creature constructs a very delicate tube, as thin as paper, ex- 

 clusively of the grains of sand agglutinated [together in an extraordinary 

 manner. The thickness of the side does not exceed a single grain, each 

 lies in its own proper place, and the whole is lined with the slightest 

 silken coating. The sand being collected at the orifice of the tube, its 

 tenant, chiefly by means of the tentacular organs, selects those which are 

 appropriate, and applies them to use. This is done only through the 

 night, all the additions being made at the orifice, and as the animal grows, 



