TONICELLA. 41 



Subgenus TONICELLA Cpr. 

 T. MARMOREA Fabricius. PI. 10, figs. 8-15. 



Shell oblong or oval, elevated, rather acutely angular ; buff, 

 closely speckled and maculated with dark red, as in Trachydermon 

 ruber. Surface densely, microscopically granulated, but apparently 

 smooth. Lateral areas not distinct. Valves beaked, umbo of pos- 

 terior valve slightly prominent, central. 



Interior rose tinted; anterior valve with 8-10, median valves 1, 

 posterior valve 8-9 slits. Sutural plates broad, rounded ; sinus 

 deep, angular. 



Girdle leathery, nude. 



The gill rows extend forward three-quarters the length of the foot, 

 each containing 20-25 branchiae. 



Length 40, breadth 24 mill. 



Length 27, breadth 16 mill. 



North Atlantic : Massachusetts Bay to Greenland ; Holland to 

 Ireland and northward. North Pacific: Aleutian Islands and 

 Japan. 



Chiton marmoreus FABR., Faun. Gronl. p. 420, 1780. FORBES 

 & HANLEY, Hist. Brit. Moll, ii, p. 414, t. 58, f. 2; t. 59, f. 4. 

 JEFFREYS, Brit. Conch, iii, p. 227; v, p. 199, t. 56, f. 7. Chiton, 

 (Tonicia) marmoreus Fabr. Smith, Ann. and Mag. N. H. (4) xx, p. 

 139 (Franklyn Pierce Bay, Greenland). ToniceUa marmorea Fabr. 

 CPR., Bull. Essex Inst. v, p. 154, 1873 ; Ann. Mag. N. Hist. (4) 

 xiii, p. 121. DALL, /. c., vi, p. 124 (anat.) ; Proc. U. S. Nat. Mus. 

 1878, p. 324. Chiton ruber SPENGLER, Skrift. Nat. Selsk. iv, p. 92, 

 not of Linne. Chiton Iwvigatus FLEMING, Edinb. Encyc. p. 113, t. 

 vii; Brit, Anim. p. 290. REEVE, Conch. Icon. t. 27, f. 179. f 

 Chiton punctatus STROM, (teste JEFFR.) Acta Nidr. iii, p. 433, t. 6, 

 f. 14. Chiton latus LOWE, Zool. Journ. ii, p. 103, t. 5, f. 6, 7. 

 SOWB., Conchol. Illustr. f. 113. Chiton fulminatus COUTH., Bost. 

 Journ. Nat. Hist, ii, p. 80, t. 3, f. 19. GOULD, Invert. Mass, i, p. 

 148, f. 3. Chiton pictus BEAN, in Thorpe's Brit. Mar. Conch, p. 

 264. Chiton flemingius LEACH, Moll. Gt. Brit. p. 230. Boreo- 

 chiton marmoreus Fabr. SARS, Moll. Reg. Arct. Norv. p. 116, t. 8, 

 f. 3. 



This species has very much the color pattern of C. ruber, but 

 may readily be distinguished by its nude, leathery girdle. Sars 

 was evidently led by this superficial resemblance to create his genus 



