243 



the miiero posterior and terminal, UMIIL: produced l.evond and above 

 the p<Meri..r oaves. 



Interior black. The sutural plates an- Mack both outside and 

 within, and an- widely separated by a broad, deep, rounded *inu~. 

 Head-valve with 8, 9 or 10, median valves 1 slit; teeth short in 

 front, longer at the sides, deeply pectinated outside. Posterior 

 valve having a broad flat crescentic callus in place of the insertion- 

 plate. 



Girdle very broad, densely clothed with short, obtuse black-brown 

 spines, tipped with whitish (fig. 43.) 



Length 50, breadth 20 mill, (measurements not including girdle.) 



Japan, at Enoshima (F. Stearns) ; Oosima (' Challenger ') ; Nag- 

 asaki (Lischke.) 



Chiton japonicus LISCHKE, Malak. Blatter, xxi, p. 22 (June, 

 1873) ; Japonische Meeres-Conchylien iii, p. 71, t. 5, f. 8-11. 

 Maugeria japonica DKR., Index Moll. Mar. Jap., p. 158. Acantho- 

 pleura (/) incana HADDON (in part), Challenger Polyplac., p. 25. 

 Not Ch. inconus Gould. Ormthochiton caliginosus CPR., MS. (spec- 

 imen described from China.) 



? Chiton De Filippii TAPPARONE CANEFRI, Zool. del Viaggio 

 intorno al Globo del la R. Fregata ' Magenta,' Malacol., p. 77, 

 1874. 



Distinguished from L. incana by the uniform black color of the 

 inner layer or articulamentum. 



The typical japonica (pi. 53, figs. 41-44) has a broad girdle, 

 densely clothed with spinelets which are nearly or quite cylindrical, 

 and are about equal in size over the entire area of the girdle. There 

 are usually some dusky bars, especially toward the ends ; and 

 the individual spinelets are dark brown, tipped with light brown 

 or cream-white. 



Var. tessellata Pils. (pi. 53, figs. 45, 46) includes specimens agree- 

 ing with the type in valve structure and coloring, but having the 

 girdle much narrower, and conspicuously varied with alternate 

 patches of white and scorched-brown or blackish. The individual 

 spinelets are larger than in typical,/"/"""'"' Iinc ^ vary much in size, 

 being small toward the outer edge of the girdle, large and flattened 

 toward the inner edge. Upon the light tracts the spine? are uni- 

 colored white ; upon the dark tracts they are reddish-brown or 

 blackish, unicolored or tipped with lighter. 



