248 CHITONID A. 
natural position; I propose, if practicable, to carry out this 
idea, though the attempt will be attended with difficulties and 
uncertainties, which need not now be alluded to. 
We are not sure that much will be gained by the investi- 
gation; it may possibly give us an idea of the affinities of 
remoter lineages with the present conditions of a particular 
genus or species ; but we think the arrival of the animal, after 
its embryonic phases, at an adult state, will not only give a 
knowledge of what it is not, but of what it actually is, and 
more will be gained by a comparative view of the mature 
organs with those of its allies. 
We apply these remarks to the present case, and thmk that 
the cesophageal nervous collar, the buccal mass, the long 
spinous tongue, the system of the circulation, and the true 
Gasteropodan foot, will inform us that such an animal cannot 
be either one of the Annelida or Cirripoda, or belong to any 
other group of the Articulata; and we beheve that the com- 
parative examination of the above-mentioned organs with 
those of the Conchifera and Patelloida will irresistibly lead us 
to acknowledge their true molluscan composition. 
The British Chitons are a group of about ten species: 
we give notes of three, selecting the C. fascicularis as the 
type. They inhabit all the zones according to their respective 
special habits. As regards British geographical distribution, 
they appear to arrive at larger growth in the northern lati- 
tudes. 
CHITON, Linneus. 
C. rascicuLaRis, Linn. et Auct. 
C. fascicularis, Brit. Moll. 11. p. 393, pl. 59. f. 5. 
Animal forming an elongated oval, the body bemg convex on 
the upper surface, and enveloped in a mantle, thin above, but 
gradually resolving into a thick, strong, broad, granular margin, 
clothed with a rigid setose white fringe, and also furnished 
on each side with eight bundles of yellowish-white bristles, 
12-15 im each, and two of the same number at the anterior 
