106 Descriptions of British Chitones and other Shells. 



Shell rather thin, semi-transparent, flattish, lyrasforin, narrow at 

 the summit, suddenly spreading in breadth towards the outer mar- 

 gin. Upper valve semi-cordate, inequilateral, flattish ; the beak 

 slightly produced, rounded, truncated horizontally to form the 

 perforation, which is large, and completed by the point of the 

 umbo of the lower yalve. Lower valve rounded, flattish, slightly 

 elevated in the middle. Both valves are regularly pectinated with 

 longitudinal, rounded, somewhat scabrous ribs, which are inter- 

 rupted by a few irregular, transverse strice of growth, giving them 

 something of a vaulted or scaly appearance. Margin of both 

 valves without the least sinuosity, regularly rounded and toothed. 

 Colour towards the beaks an obscure reddish brown, gradually 

 becoming fainter towards the margin which is yellowish white. 

 Inside yellowish white. Animal bright orange-red. Pedicle orange, 

 terminating in a short tuft of brown fibres by which it attaches itself 

 to the rocks. Length rather more than -j^- of an inch ; breadth 

 rather less : — that is, the shell is -y'^ of an inch longer than broad. 



Found by M. J. Berkeley, Esq. attached to the under side of 

 a loose rock on the beach laid bare by a remarkably low spring 

 tide, about 50 yards south of the Custom-house at Oban. In the 

 same place I found Chiton latus^ Emargmula conica in abundance, 

 Fissurella grceca^ Valuta alba of Turton's Conch. Diet., and a num- 

 ber of other interesting shells which are only to be obtained by 

 turning over the broken rocks that lie on the beach and are ex- 

 posed by low spring tides. I never succeeded in obtaining a se- 

 cond specimen of the Terebratula. 



This species appears to me perfectly distinct from T. Caput- 

 Serpentis of Lamarck and Chemnitz, as I have satisfactorily as- 

 certained by comparison with a specimen obligingly lent me by 

 Mr. G. B. Sowerby. It is distinguished by not having the slightest 

 sinuosity in the front margin, or depression in the upper valve 

 running from the beak to the margin ; by its regular ribs instead 

 of striae, and strongly toothed margin. Its general appearance 

 and shape are also very different; and the perforation is perfectly 

 horizontal, not oblique as in T. Caput-Serpentis, though this is 

 not perhaps any certain distinction. It approaches much more in 

 general appearance the shell figured in the Ency. Meth. pi. 246. 



