104 Descriptions of British Chitones and other Shells. 



Shell strong, broad, slightly ovate, rather wider behind than 

 before, carinated. Valves beaked, smooth, shining ; when seen 

 through the lens minutely granulated. Marginal ligament per- 

 fectly smooth, simple, without the least powdery appearance or 

 reticulation. Fringe very short and indistinct. In the number 

 of the marginal teeth this species approaches nearest to C. ruber. 



Colour dark rufous olive, mottled ; sometimes approaching to 

 SI dark slate-colour ; generally with a rufous or tawny tinge. 



Length rather more than an inch; breadth about -|- of the length. 



From Oban ; on the under side of loose rocks on the beach, 

 (about 50 yards south of the Custom-house,) which are only un^ 

 covered at spring tides. Also at Appin, Captain Carmichael. 



Whether this shell is the real C. marginatus of Pennant and 

 others, I have found it impossible to determine. I have little 

 doubt in asserting my opinion that it is the shell described under 

 that name by Montagu. His description is perfectly consistent, 

 as far as it goes, with my shell ; and his observation under Clcevis 

 of the breadth of his C. marginatus, and the remark that it wants 

 the serrated edge and reflected margin of Pennant's C. marginatus 

 confirm this idea.* The latter character however has at once the 

 appearance of being a very doubtful one, probably only owing to 

 the contraction of the margin in dried specimens, and to be seen 

 in most of my specimens of C.laius: — and the first of the serrated 

 margin has not at all the air of a distinguishing character, at least, 

 if I am right, in supposing it to mean the llgamental margin. 



The figure in Argenville t. 25. f. M. referred to by Wood for 

 C. marginatus is certainly nothing but a large specimen of C. 

 cinereuSf and does not present any of the characters just men- 

 tioned. The figure given by Wood himself for C. marginatus, I 

 have referred without any hesitation to C. cinereus ; and if I am 

 right in supposing a mistake to exist between the two references, 

 (as explained under C. cinereus,) his figure 4 will be a tolerable 

 representation of my C. latus. The figure of the Ency. Meth. 



* Further confirmation as to locality is to be found in an observation on 

 this species in the Supplement to Test. Brit, mentioning that the separate 

 valves have been found on the Scotch Coast half an inch wide (the general 

 size of my specimens.) 



