142 SUPPLEMENT 
nervous system not collected into a spinal marrow, but merely 
into a certain number of medullary masses, dispersed over 
different parts of the body, the principal of which, termed the 
brain, is situated on the cesophagus, which it encircles with a 
nervous collar; blood cold, whitish or blueish; circulation 
double; hearts often numerous. 
M. de Lamarck admits nearly the same definition: ovipa- 
rous animals, with soft body, not articulated in its parts, and 
having a variable and muscular mantle; respiration by diver- 
sified gills; a brain, some ganglia, and nerves to give sensi- 
bility and irritability to the organs; but no spinal marrow ; 
conglomerate glands; a shell enveloping or enveloped, and 
sometimes none. 
M. de Blainville proposes the following : 
Animals with the body and its appendages soft, not arti- 
culated, enveloped in a skin or muscular dermis (mantle), of a 
variable form, in or on which is most frequently developed a 
calcareous part (the shell), of one or two pieces; circulation 
complete, with white blood, heart essentially aortic, and supe- 
rior to the intestinal canal, except in the brachiocephala ; 
respiration aquatic or aerial; nervous system composed of a 
cerebriform ganglion, sub-cesophageal, communicating with 
the ganglia of the different functions; those of locomotion 
being lateral. 
As to the place of the mollusca in the series of animals, 
Aristotle separates his two groups by the crustacea. Aldro- 
vandus, Johnston, Ray, Linnzus, his whole school, and M. 
Dumeril, place them after the insects; Cuvier, Lamarck, and 
their followers, place them at the head of the invertebrated 
animals. 
In considering these animals as constructed on a peculiar 
plan, and forming a distinct type, they might even be 
approximated to man, the top of the animal scale, as may the 
