I j\Ir. W. H. BetisoJi on some new ^«?iaft Cyclbstomata. 283 



st<fe^he body, which do not nearly occupy half the extent of its 

 di'cumference. The inner surface of the mantle in different in- 

 dividuals exhibits the various hues of flesh-colour : the foot is a 

 dull muddy purple. The margin of the mantle is powdered with 

 minute, granular, dark, sand-like points, and fringed with veiy 

 short, fine, close-set, pale yellow filaments. This species, at 

 Exraouth, is rarely met with in the littoral or laminarian districts ; 

 its habitat is within the coralline limits, and it is scarce. 



°^ J-'^ ' Chiton cinereus, Linnaeus. 



Chiton marginatus, Auctorum. 



i^£ The same remarks apply to this as to the preceding species, 

 from which the only decided variation is the greater number of 

 branchial leaflets, being seventeen on each side, of a dull flesh- 

 colour, and occupying considerably more than half the circum- 

 ference of the mantle, which on its inner surface is also flesh- 

 colour. A fine, setose, short, thick, pale rufous fringe clothes the 

 margin of the mantle, which is minutely granulated, as if aspersed 

 with dark sand-points. This very common species is strictly, at 

 Exmouth, a littoral one, and rarely found beyond its limits. 



The other British Chitons are — the C. discrepans of Brown, C 

 Hanleyi, C. ruber, C. leevis, C. cancellatus, C. albus, C. marrnoreus, 

 which latter is the C. lavigatus of authors, and the ' latus ' of the 

 Rev. R. T. Lowe. The C. discrepans of Brown is not strictly 

 one of our indigena, being confined to the Guernsey and Channel 

 Islands : it is not improbable that this and the C. fasdcularis are 

 identical, and only exhibit the specialty-differences of locality] -ti 



I am. Gentlemen, 



Your most obedient servant, 



William Clark. 



— ^ liiido aw 



XXVL — Additional Character of the Shell of the Cyclostomatous 

 genus Alyeseus of Gray, loith descriptions of its Animal Inha-, 

 bitant, — of a fourth species, — and of other new Indian Cyclo- 

 stomata ; also. Remarks on an unrecorded Character in Diplom- 

 matina. By W. H. Benson, Esq. 



The existence of a sutural callus in a third species of Gray's 

 genus Alycceus, described below as A. Urnula, induced a con- 

 jecture that the feature might be generic, and that it had been 

 overlooked in the single remaining Cochin Chinese species 

 A. ffibbus, as well as in A. strangulatus and constrictus, the first 



19* 



