Phyllidiacea.] 



MOLLUSCA. 



67 



colour various, dark chocolate-brown, burnt terra-sienna, or 

 yellowish-white, with clouds, streaks, or spots. Length not 

 quite half an inch ; breadth somewhat more than half its 

 length. 



This shell has much the general appearance of the former 

 species, but its marginal teeth sufficiently characterise it as dis- 

 tinct. 



Found at Oban and Appin, on the Argyleshire coast, but is 

 very rare. The handsome specimen from which I drew fig. 21, 

 was sent me by Captain Carmichael. 



Section III. — Marginal ligament smooth. 



13. Chiton l^evigatus, pi. XXI, f. 1 and 16. 



Chiton latus, First Ed., pi. 35, f. 1 and 16; Chiton leeviga- 

 tus, Fleming, Edin. Ency., p. 103; Lowe, Zool. Journ., II, p. 

 103, pi. 5, f. 6, 7- 



Shell oblong, broad, somewhat wider behind than before, and 

 slightly carinated ; valves smooth, shining, and beaked, with 

 minute granulations ; marginal ligament quite smooth, simple, 

 with a very short and indistinct fringe ; first valve with nine 

 broad teeth, and the terminal one with eight broad teeth ; 

 colour generally dark reddish-olive, and mottled with a paler 

 hue, in others approaching to dark slate-colour, and sometimes 

 reddish-brown. Length somewhat more than an inch ; breadth 

 three-fifths of its length. 



In the character of the marginal teeth, this shell approaches 

 that of C. ruber. 



Found by Mr. Lowe, at Oban, Argyleshire, on the under side 

 of loose rocks, which are only uncovered at Spring tides, about 

 fifty yards south of the Custom House, and also at Appin, by 

 Captain Carmichael, who sent me the specimen from which fig. 

 1 was drawn. Fig. 16 was taken from a specimen found by my 



late friend Mr. Hancock, of Newcastle-upon-Tyne, below Tyne- 

 mouth Castle, in 1809; so that he was the discoverer of the 

 species. It was found plentifully in Zetland and Loch Broom, 

 by Dr. Fleming. 



Section IV. — Doubtful species. 



14. Chiton discors. 



Cliilon discors, Maton and Rackett, p. 20; Chiton septem- 

 valvis, Montagu, p. 3. 



" With seven carinated valves, strongly beaked ; the five 

 middle ones divided transversely from the anterior base to the 

 beak, the hinder compartment very fine shagreen, the other 

 very smooth, or faintly striated transversely; the extreme valve 

 at each end rufous-brown, the rest generally dark cinereous; 

 beaks frequently rufous ; margin moderately broad, and finely 

 reticulated ; shape of C. Icevis. Length half an inch. 



" Found in Saleomb Bay, but rare." — Montagu. 



Whether this is a distinct species, it is difficult to determine; 

 although I think in all probability it is, as well as the following 

 species, lusus natures. Montagu, in his Supplement, says, "we 

 are inclined to believe this an accidental variety of C. mar- 

 ginatus." 



15. Chiton quinquevalvis, pi. XXI, f. 22. 

 Chiton quinquevalvis, First Ed., pi. 35, f. 22. 



Shell oval, carinated, of a reddish-gray ; with five consider- 

 ably beaked valves, covered with strong, shagreen-like papilli ; 

 valves divided on each side by a deep groove, inclining obliquely 

 from the flat edge towards the beaks, where the grooves termi- 

 nate; margin rather broad, covered with extremely fine, irregu- 

 lar, shagreen-like papilli, with the edge ciliated. Length three 

 and a half eighths of an inch ; breadth three-eighths. 



Found at Tenby, by General Bingham. 



