ACEPHALA LAMELLIBRANCHIATA. 31 
convey the blood throughout the system, and another visible 
elaborate apparatus to eliminate the vital element, that she 
would stop in the midst of her career, and, instead of a set 
of vessels to convey it back to the branchiz for oxygenation, 
substitute and allow the stream of vitality to find its way 
through a mixture of cavernous sinuosities, and percolate 
amidst the ordures of the visceral contents to the mouths of 
the branchio-cardiac vessels, to pass it to the respiratory me- 
chanism to repair the usual exhaustions and adscititious impu- 
rities of its passage. 
Neither of these opposite views can be verified in the living 
animal, and the examination of the dead one is equally unsa- 
tisfactory, because uncovered sinuous canals may appear to 
exist in the tissues; but who can say that the excessively thin 
walls may not have vanished by contraction attendant on the 
peculiar mode of death, leaving only the simuosities of their 
sites ? 
The above remarks are confined to the circulation of the 
blood. I fully admit that in many of the Mollusca, aquiferous 
canals and pores exist in the tissues of the foot and its pedicle, 
and other organs for the admission of water to assist in pro- 
moting the tension of those organs in aid of locomotion; but I 
do not believe that the water enters the visceral regions except 
by the mouth, unless in consequence of a rupture of the parti- 
tion-membrane between the cavities of the foot and the abdo- 
men; it has been stated that the Lucine are instances of the 
water passing through the foot into that cavity. 
For these reasons we repudiate, as contrary to nature and 
all analogy, the doctrine of even a qualified lacunose system 
for the blood circulation; that is, of its bemg sent by arteries 
to all parts of the organism, and returned partly by walled 
vessels, and partly by smuous canals worked out of the paren- 
chyme. 
And in the tribes of inferior organization to the Mollusca, 
we consider, however imperfect the mechanism of the susten- 
tation and circulation may be, that both these functions are 
distinct, and in no case confounded; we believe that nine- 
tenths of the matter that has been advanced by authors on 
