CHAPTER II. 
MOLLUSCA. 
I SHALL treat of the Mollusca before the Articixlata ? 
because as a group their intelligence is not so high. 
Indeed, it is not to be expected that the class of 
animals wherein the 4 vegetative ’ functions of nutri- 
tion and reproduction predominate so largely over the 
animal functions of sensation, locomotion, &c., should 
present any considerable degree of intelligence. Nevei- 
theless, in the only division of the group which has 
sense organs and powers of locomotion highly developed 
— viz., the Cephalopoda — we meet with large cephalic 
ganglia, and, it would appear, with no small develop- 
ment of intelligence. Taking, however, the sub-king- 
dom in ascending order, I shall first- present all the 
trustworthy evidence that I have been able to collect, 
pointing to the highest level of intelligence that is at- 
tained by the lower members. 
The following is quoted from Mr. Darwin’s MS. : — 
Even the headless oyster seems to profit from experience, 
for Dicquemase ( 6 Journal de Physique/ vol. xxviii. p. 244) 
asserts that oysters taken from a depth never uncovered by the 
sea, open their shells, lose the water within, and perish; but 
oysters taken from the same place and depth, if kept in reser- 
voirs, where they are occasionally left uncovered for a short 
time, and are otherwise incommoded, learn to keep their shells 
shut, and then live for a much longer time when taken out of 
the water. 1 
1 This fact is also stated by Bingley, Animal Biography , vol. iii. 
p. 454, and is now turned to practical account in the so-called ‘ Oyster- 
schools ’ of France. The distance from the coast to Paris being too 
great for the newly dredged oysters to travel without opening their 
shells, they are first taught in the schools to bear a longer and longer 
exposure to the air without gaping, and when their education in this 
respect is completed they are sent on their journey to the metropolis, 
where they arrive with closed shells, and in a healthy condition. 
