248 CHITONIDJE. 



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 think that 

 the ossophageal 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 believe 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, Linnaeus. 



C. FASCICULARIS, Linn, et Auct. 

 C. fascicularis, Brit. Moll. ii. p. 393, pi. 59. f. 5. 



Animal forming an elongated oval, the body being 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 in each, and two of the same number at the anterior 



