ACANTiii >ri I ri: \ 



Keadilv rec.. L r ni/ed l>y the Mack, irranulated ridtt, an. I HBOOthet 



;riped rid.ire, in connection with the peculiar insertion-plate of 



tin- tail valves. Smith has placed the species with douht in the 



synonymy of A iiiii[icr, where it certainly does not belong ; and 



Martens, also erroneously, suggests its identity with ('It. i>ctli<>l<itn.< 



Sow. 



The insertion-plate of the tail-valve, while in some specimens 

 somewhat uneven, is not often so serrated as in A. br'-rinftinosa. It 

 further differs from that species in the striped back and the interior 

 coloration. The crescent-shaped black patch behind the sinus inside 

 is square or forked at the ends, as in A. granulata, and the edge of 

 the sinus is white. 



A. BRI:\ isriNosA Sowerby. PI. 47, figs. 18, 19, 20, 21. 



Shell oblong oval, depressed, each valve beaked and concentrically 

 rugose-granuliited. Color black, the girdle narrow, clothed with 



The valves concentrically wrinkle-grained at the sides of the 

 central areas, and the ill-defined lateral areas are cut into granules 

 by concentric and radiating grooves. End valves finely grooved radi- 

 ally t finely wrinkled concentrically ; mucro posterior, prominent and 

 rather acute. 



Interior blackish-brown or /nirple-browti except the sutural- and 

 insertion-plates which are white. Sinus broad, deep, rounded. 

 Anterior valve having 7-8, central 1, posterior 2 slits and a number 

 of irregular serrations ; anterior teeth moderately long, finely pect- 

 inated outside ; posterior teeth very short, blunt, obsoletely pectinated. 



Girdle rather narrow, clothed with rigid black spinelets tipped 

 with buff. 



Length 42, breadth 26 mill. ; divergence about 130. 



Johanna, Comoro Is. (Cuming, Cpr.) ; Zanzibar (Cpr.) ; Cape of 

 Good Hope <m<! Mnd<tga*cnr (Paris Mus.) ; Strait ufSnint Vincent, 

 Cape Verde I*. (Cessac.) 



Chitnn I,,-, -i-i-tplnoxua SOWB., Mag. of Nat. Hist. 1840, p. 287. t. 

 xvi, f. 1; Conchol. Illustr., f. 136. KI:I:\I:, Conch. Icon., f. 52. 

 Acniitln>pl'-imi brcvi-xpinoaa ROCHEBR., Nouv. Arch, du Mus. J881, 

 p. 240. 



Part of the localities given above are probably incorrect, A good 

 many shells procured at " Cape of Good Hope" and "Zanzibar" 



