ie * SE eee, ok 4 
294 Mr. W. Clark on the Animal of Kellia rubra. 
pygmeus, and send it to Bath in a moist state with a small phial 
of sea-water. It arrived yesterday by the post, and I found therein 
twelve specimens of Kellia rubra, which being placed in a watch- 
glass in sea-water showed themselves as lively as if examined at 
Exmouth. By the superior appliances used I at once saw what 
I had overlooked at Exmouth, and that Mr. Alder is perfectly right 
in stating the tube to be open below; all the animals repeatedly 
inserted the foot into the canal, and by thus displacing its sides, 
showed distinctly it was an open fold of the membrane ; but the 
moment the foot was withdrawn, it reverted to its usual perfect 
tube-like aspect ; indeed the most accomplished observer might 
be deceived, as it appears M. Philippi was. In fact this canalis . 
a mere prolongation of the mantle, which is entirely open for 
more than half the ventral range, for the working of the foot 
and byssal apparatus. 
But Mr. Alder is mistaken in supposing the tube-like fold to 
be for branchial purposes; no currents, at least branchial ones, 
enter therein or issue therefrom ; it is a fold merely subservient 
to locomotion ; this I perceived to be the case in a very short 
time, as I found the movements of the foot and tube-like canal 
to be nearly isochronal and dependent on each other, as when 
the foot was extended and fixed for a forward movement, the 
tube was also exserted, and by its muscular retractive power, in 
contemporaneous action with the foot, the shell was advanced in 
progression. It will now be asked, where then is the branchial 
aperture? This I have also satisfactorily discovered ; it is the 
posterior opening which has passed for the anus, and is in reality 
a considerable elongated oval fissure, having its periphery slightly 
thickened or margined, and divided from the rima magna of the 
byssus and foot by a strong, narrow, transverse septum; from 
the termination of this opening the mantle is closed to the um- 
bones ; within this fissure I distinctly saw a part of the points of 
the branchie, and it was regularly dilated and contracted as the 
currents of sea-water,were received, and after aération of the cir- 
culating fluid expelled, m a similar manner to the action of systole 
and diastole. I must now speak of the anus, which I had also 
the good fortune to discover ; it is placed at the posterior end of, 
and under the branchial aperture, and is a very minute, and for 
a part of its length, a disunited pendulous tube ; its orifice is not 
one-tenth part of the size of the branchial opening; from this 
internal tube I repeatedly saw the rejectamenta expelled in small 
cylindrical light yellow or grayish pellets, which, falling within 
the cavity of the fissure, were instantly ejected; this oval aper- 
ture cannot even be called sessile, it is only a slit, serving as a 
common canal, for supplying the branchie with water and for the 
passage of the feces; these are the only ¢wo openings in the 
