AMPHITEITE. 219 



laria dichotoma, one of the most delicate among the Scotish corallines. 

 Three weeks after I procured them, none spread above half a line across 

 the funnel. Yet all were even then industriously employed in enlarging 

 their dwellings. 



At that early period the feathered branchiae are very few, not ex- 

 ceeding six or eight in number ; nor are the cilia clothing them more 

 than twelve on each side, being proportionally scanty, compared with 

 future accessions. But now was an admirable spectacle presented by the 

 microscope, for the field of which so small an object was most suitable. 

 The whole external organs of those minute artificers were in active ope- 

 ration. A current of thin muddy matter, supplied by many other cur- 

 rents passing along the cilia, was transmitted down the rib of each branchial 

 feather, here receiving them as in a common channel. Thence the whole 

 descended for preparation below, and application to its definite purpose. 



I have compared each of the branchise to a feather, consisting of a rib 

 bordered by its cilia, but whether these be clothed with similar organs, 

 invisibly feeding them with sundry particles, merits investigation. I 

 feel much disposed to credit their existence ; in which event, those we 

 have discoursed so freely about would become secondary, instead of dis- 

 charging a primary office. Should there be no such invisible primary 

 organs, the cilia bordering the branchial rib have themselves the faculty 

 of promoting the descent of the muddy matter down to the centre. 



In general these young animals had six branchial feathers ; that re- 

 presented fig. 8, had seven. The longest plume among them expanded 

 about a line and a half, the tube rising about four lines ; the trowels, 

 while clasping over the edge of the orifice, were white and fleshy. 



A waving depression seemed to run up the centre of the rib. No 

 semblance of circulation was perceptible. 



These nascent animals survived several months, during which the 

 dimensions of their tubes were considerably augmented. Plate XXX. 

 fig. 7, 8. 



On investigating the nature of their dark soft leathern-like tube, its 

 composition proves to be an earthy coating, which invests a thick adhe- 



