12 CLASS Ill. GASTEROPODA. ORDER II. CYCLOBRANCHIATA. 
P]. CXXXIV. Fig. 151. 
Cuiron sprnosus, Bruguiére, Journ. d’Hist. Nat., vol. i. p. 25. pl. 2. 
f.1 and 2. Sowerby, Genera of Shells, fig. 1. 
Pl. CXXXIV. Fig. 152. 
Cuiron runicatus, Wood, Gen. Conch., pl. 2. f. 1. 
Pl. CXXXIV. Fig. 154. 
Curron Cuitensis, Frembly, Zool. Journ., vol. ui. p. 203. pl. 17. f. 6. 
Deshayes, new edit. of Lamarck, vol. vil. p. 493. 
CHITONELLUS, Lamarck. 
Corpus repens, eruceforme, valvis octo testaceis instructum ; valve 
longitudinales, sejuncte, per medium pall externe seposite, versus 
extremitatem anticam appropinquantes, in cute crassa, plerumque 
coriacea, profundeé inserte. 
The Chitonelli were separated from the Chitones by Lamarck ; and it is 
not without some consideration that we differ from such authority as that 
of De Blainville, Sowerby and Deshayes as to the propriety of reuniting 
them. We cannot attach any material value to the difference in the size 
and shape of their shells, but the change in the position and arrangement 
of the valves is curious and important. In the Chitones they are firmly set 
in a strong marginal cartilage, fitting and moving upon each other like 
plate-armour with the motion of the animal; and although the Chiton 
amiculatus has its shell entirely concealed within the mantle, still the 
order and disposition of the pieces is the same. In the Chitonelli, on the 
contrary, the valves do not so much as touch each other, nor are they set 
in the same cartilaginous frame, but inserted or unconnectedly dotted, as 
it were, down the middle of the mantle. In some specimens of the 
