142 Mr. W. Clark on the Animal of Kellia rubra. 
oblong, acuminated gradually, and sharply attenuated at the 
apex, rounded or subtruncated, and somewhat inzequilateral at 
base, 3 inches long, 1% inch broad, upon a thick short petiole 
of 2 lines in length. The flowers, sometimes in pairs, grow late- 
rally at the base of the petiole ; the peduncle is refracted, = to 
1 inch long, and covered with long glandular hairs mixed with 
shorter stellate pubescence ; the calyx, also tomentose, is 8 lines 
long, 6 lines across, inclosing a small globular berry 4 lines in 
diameter. 
XVIII.—On the Animal of Kellia rubra. 
By W. Crark, Esq. 
To the Editors of the Annals of Natural History. 
GENTLEMEN, Beacon Hill, Exmouth, Devon, July 5, 1849. 
I ventuRE to trouble you with a few observations in reply to 
Mr. Alder’s last paper, in the ‘Annals’ of this month, on the 
subject of Kellia rubra, and then I hope to retire from the field. 
I have had ample scope allowed; and though you have not in- 
terrupted the discussion, by issuing the editorial veto, 
“‘Claudite jam rivos, pueri, sat prata biberunt,” 
still we ought to keep in mind the phrase, 
“ Est modus in rebus.”’ 
Mr. Alder still contmues to rely on the point that the regular 
ingress and egress of the branchial currents, and the regulation 
thereof, in the bivalve mollusca, are produced by the action of 
the vibratile eilia, which clothe the branchial lamin; I differ 
from his views, and think this doctrine entitled to no confidence, 
and that the cause is inadequate to the effect propounded. 
The branchial cilia have very different functions ; their sole use 
is to beat and subdivide the water, to facilitate the elimination 
of the vital principle therefrom, after it has been admitted into the 
branchial cavity by the opening of the valves of the animal, by 
the relaxation of the adductor muscles, and from whence the im- 
pure water is discharged by their contraction at the same points, 
ventral or siphonal, or a combination of both, as the animal may 
happen to be closed, or open mantled, at which it enters, and a 
fresh supply of the pure element is received to fill the vacuum 
caused by its expulsion. 
Great misapprehension has arisen from confounding the func- 
tions of two different sets of organs, attributing to the one the 
uses of the other, the real functions of which have altogether 
been unnoticed. 
The assumed regularity of the admission and discharge of the 
