30 THE VOYAGE OF H.M.S. CHALLENGER. 



posterior valves. Acanihopleura incanus presents us with the anomaly of a Chiton with 

 the anterior and intermediate valves quite similar to those of the " Regular" Acanthoidea, 

 and with a posterior valve resembling that of the "Irregular" Placiphoroidea ! An 

 inspection of Carpenter's MS. proves that even at the time of his death he had not 

 unravelled this admittedly difficult genus to his own satisfaction. 



Dr A. T. de Rochebrune has recently briefly described, without figures, the following 

 species : — Acanthopleura quatrefagei, 1 n. sp., Cape of Good Hope. Acanthopleura vail- 

 lantii, n. sp., Suez Canal ; Acanthopleura afra, n. sp., Cape of Good Hope and Madagascar ; 

 Acanthopleura rawalciana, n. sp., Rawak, New Guinea ; and Acanthopleura balansce, 2 n. sp., 

 Australia and New Caledonia. 



Subgenus Francisia, Carpenter. 



" Acanthopleura : valvis partim immersis, planatis ; laminis centralibus pleurifissatis ; 

 sinulobato" (Dall, 1882). 



Francisia spinosa (Bruguiere). 



Chiton spinosus, Bruguiere, Journ. d'Hist. Nat., 1792, voL i. p. 25, pi. ii. figs. 1, 2. 



„ ,, Sowerby, Genera of Recent Shells, 1820-25, pL cxxxix. fig. 1 ; and Conch. Illust., 



1840, p. 1, pi. clxxv. fig. 151. 

 „ ,, Reeve, Conch. Syst., 1842, vol. ii. p. 12, pi. cxxxiv. fig. 151; and Conch. Icon., 



1847, pi. ix. fig. 51. 

 Maugeria spinosus, Gray, Guide MolL Brit. Mus., 1857, p. 184. 

 Chiton spinosus, Adams, Genera Recent Moll., 1858, vol i. p. 475. 



Habitat. — Station 187. September 9, 1874. Lat. 10° 36' S. ; long. 141° 55' E. 

 Albany Island, Cape York, North Australia. 6 fathoms. Coral mud. 

 New Holland. 



The shell has concentric lines of growth, and is roughened on the terminal valves and 

 lateral areas, but is otherwise quite smooth. The laminae of insertion are very large. 

 There are about seventeen irregular slits in the anterior valve and twelve in the posterior ; 

 there is one lateral slit. The teeth are very long and finely grooved ; eaves practically 

 non-existent. 



The upper surface of the shell is of a uniform black colour ; the under surface of a 

 lustrous madder pink. Insertion plates white. 



1 Journ. de Conch., t. xxi. p. 42, 1881. 



2 Bull. Soc. Philomath. Paris, ser. 7, t. vi. pp. 192, 195, 197, 1882. 



