CHNOCHIT< 



A relic <nnl .\nrlli At/anlir Sects ; Grccn/n n<l ; /r/7////// 

 tn'i'i/rii ; Xnimlimn'iii ; />'/// /W/ n{ .}/,,,, 



S/. Lawrence, Maine, and south to Mauaehutettt \ 



In tlir r,icifii- from Arctic Ocean, xo /f///. In tin- .S'/M/w////// /..-., n'ent to 

 h'l/xkn. Low water to :!:;7 f'ms. 



Chiton ulbii* LINM:, Syst. Nat. xii, p. 1 107.- Lowi:, />.]. .I.-urn. 

 iii. p. SO. Sown., Conch. III. f. !>'.), UK).- GOULD, Inv. Rfa 

 loi). f. 21. MlDD., Mai. Ross, i, p. 120. I-'OKI:I.< A- HANI i;v, 

 I'.rit. Moll, ii, p. 405, t. 62, f. 2. STIMPSON, Sh. of N. En#l. p, 

 inv. of (Jrand Manan p. 2'J. .Ji:i'F., Brit. Conch, iii, p. L'-jn ; v. p. 

 199, t. 56, f. 3. BINNEY, in Gould's Invert. Mass. p. 265, i. 51 

 ? Chiton onjzn S]-I:N,;IJ:K, Skrift. Nat. Selsk. iv, hft. 1, 17'.7, teste 

 JiflV. Ch. selloides LOWE, Zool. Journ. ii, p. !().', t. ">, f. 3. 

 WOOD, In<lcx Test., Suppl., t. 1, f. 9. Ch. sagrinatus Connorv, 

 Amer. Journ. Sci. xxxiv, p. 217, 1838; Bost. Journ. ii, p. 82. 

 Lejttochiton albus H. & A. AD., Gen. Rec. Moll, i, p. 473. Chitmi 

 (Lepidopleurus) albus JEFFREYS Brit. Conch, iii, p. 210. Ch. 

 (Lophyrus] albus JEFFR. P. Z. S. 1882, p. 669. Lophyrus fi/lm* 

 SARS, Moll. Reg. Arct. Norv. p. 114, t. 8, f. 2 (? not t. I, f. 9). 

 ? Ch. minimus GMEL., Syst. Nat. xiii, p. 3205. Trachydermon 

 albas CARPENTER, New Engl. Chitons, Bull. Essex Inst. v. p. 153; 

 MS. p. 15. DALL, Proc. U. S. Nat. Mus. 1878, p. 322. 



This well known Arctic and subarctic species is intermediate 

 between Tr. cinereus and Tr. ruber in sculpture. The granulation 

 is much finer than in the former of these, but is on the same general 

 plan. 



On pi. 6, figs. 32-34, is copied a Carpenterian drawing of the 

 interior of Tr. albus. It is, however, incorrect, the form of head 

 and tail valves being unusual, and the slits of the latter entirely 

 incorrect. The central valve is well represented however. The 

 tail valve of a specimen from Grand Manan, drawn by the writer, 

 is shown in fig. 38 of plate 7, correctly delineating the slits. 



I. EXARATUS Sars. PL 7, figs. 39-49. 



Elongated, oblong-elliptical, strongly convex : valves distinctly 

 obtusely carinated medially. Anterior valve nearly semicircular 

 in front; the posterior edge forming an obtuse reentrant angle, 

 with a rounded notch in the middle; surface di.-tinrtly, radially 

 grooved with single rows of rounded granules between the grooves, 

 becoming larger toward the margin. 



