54 Mr. J. Alder on the Animal of Kellia rubra. 
structure disables it from procuring any food but what is floated 
into its shell by the agency of water, can possibly live perma- 
nently out of that element. It is true that oysters and several 
other bivalves can endure a sort of torpid existence out of water 
for some time when the valves are closed to prevent the evapo- 
ration of moisture from the gills; but Mr. Clark supposes this 
little Kellia able to walk abroad beyond tide-marks, notwith- 
standing the desiccation of the branchiz which the opening of 
the valves might cause. 
Should I have succeeded in showing that the impossibility or 
even improbability of my views being correct has not been esta- 
blished, the following interesting letters from Mr. Cocks, de- 
tailing a series of observations kindly undertaken at my request, 
will go far to prove my original statement, that the anterior 
siphon in Kellia rubra is the ingress channel through which 
water is supplied to the branche and to the mouth. The mode 
by which it makes its exit has not been so satisfactorily made 
out, but I have great confidence that my views and observations 
on this point will also ultimately be confirmed. However that 
may be, if one fact has been established in the animal ceconomy, 
something has been gained. Mr. Cocks’s observations appear to 
have been more especially directed to the anterior siphon. 
I am, dear Sir, very truly yours, 
JosHua ALDER. 
My DEAR Sik, Falmouth, June 8, 1849. 
I have repeated the experiments on Kellia rubra and K. subor- 
bicularis, and the results confirm my former statements*. I 
witnessed the ingress of water, atoms, crustacea, &c., very di- 
stinctly into the anterior siphon of both species, and also the ex- 
pulsion of feces from the posterior siphon, but have failed in toto 
to prove the current of water posteriorly in either, or the expul- 
sion of water from the anterior siphon of A. rubra, although in 
K. suborbicularis it takes place : viz. a K. suborbicularis that had 
been confined several months in one of my experimental bottles, 
was put into awatch-glass of fresh salt water. It sent forth the 
anterior siphon : the orifice expanded, and the water, atoms, &c. 
flowed freely into it for a few seconds: it then closed the aperture, 
contracted in length, and with a slight convulsive jerk of the 
animal and a partial closing of the valves, sent forth a jet of 
water, apparently free from any admixture, through the anterior 
tube. The operation was performed twice or thrice in a 
minute. 
* Mr. Cocks’s first letter is not inserted, as the contents of it are sufficiently 
illustrated in the sequel. 
} This action, aceording to Mr. Cocks’s description, appears to take place 
more decidedly and frequently when the animal is removed from impure 
