AM PHITRITE. 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 branchiz 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 ina common channel. Thence the whole 
descended for preparation below, and application to its definite purpose. 
I have compared each of the branchiz 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, imstead 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. 
fie gO 
On investigating the nature of their dark soft leathern-like tube, its 
composition proves to be an earthy coating, which invests a thick adhe- 
