REPORT ON THE POLYPLACOPHORA. 25 



lata from the Barbadoes. The posterior valve has nine or ten slits, long teeth, short 

 eaves ; in colour and general appearance it resembles Acanthopleura spiniger, except that 

 the shell is very much thinner, the insertion plates whiter, and the jugum, as in the other 

 valves, of a deeper and madder-coloured brown, instead of the nearly uniform slaty 

 brown which characterises what I consider to be the typical species. The striation in all 

 the teeth is also more delicate. 



The girdle is very closely beset with fairly long, but thin calcareous spines, which are 

 black, with white tips, and in my specimens present no banded arrangement. 



Acanthopleura (?) incana (Gould). 



Cliiton incanus, Gould, Proc. Boston Soc. Nat. Hist., 1846, vol. ii. p. 145, and Wilkes' Explor. 



Exped., 1852, p. 315, pL xxviii. figs. 432, 432a; also Otia, p. 6. 

 Maugeria incanus, Gould, Otia, 18G2, p. 248. 



Acanthopleura incana, E. A. Smith, ZooL Collect. H.M.S. "Alert," 1884, p. 81. 

 Chiton piceus (?), Angas (not of Gmelin), Proc. Zool. Soc. Lond., 1867, p. 223. 



Habitat. — Oosima, Japan. Specimen B. 



Port Jackson. 6 fathoms. Specimen C. 



New South Wales (Gould) ; Port Jackson (Coppinger) ; Stewart Island, New Zealand 

 (C. Traill in British Museum). 



The shell in the specimens from Japan is very finely tubercular, with concentric lines 

 of growth ; the lateral areas are scarcely apparent ; dark brown in colour, with a pale line 

 on each side of the jugum. 



The girdle spines in the Japanese specimen (B.) are mostly dark brown in colour tipped 

 with pale brown or white ; a few are white, and only very indistinctly suggest a banded 

 arrangement. 



A second specimen from Japan (A., given me by Mr Dall) has distinct bands for the 

 first, second, third, and seventh valves, those for the fourth, fifth, and sixth valves are 

 confluent, and nearly the whole of the girdle round the last valve is black. 



The shell in the example from Port Jackson (C.) is sculptured with concentric waved 

 lines, the inconspicuous lateral areas with short, very fine radial ridges ; colour as above. 



The girdle spines of this specimen are somewhat smaller than in the former, and are 

 arranged in alternate black and white bands, only slightly differing on the two sides. 

 There is a broad black band at the sides of the first and last valve, a narrow one opposite 

 the second and third valves, a broad band extending along the fourth and fifth valves, 

 and a narrow one between the sixth and seventh valves, making six on each side. The 

 dark spines are also tipped with a lighter colour or with white. 



In Gould's type-specimen there are ten black bands on the girdle, the anterior and 

 posterior valves each having two pairs. The spines of the girdle are much more uniform 

 in size than in the preceding species. 



(ZOOL. CHALL. ESP. FART XLIII. 1886.) Uu i 



