ISCHNOCHITON. 81 



The girdle is reddish-brown, covered with minute elongated 

 scales. 



The gills extend forward to the middle of the body. 



Length 20, breadth 12 mill. Alaskan specimens grow to the 

 length of an inch. 



Arctic and northern seas of Europe; south to Massachusetts Bay ; 

 N. Pacific and Bering's Sea from Pribiloff Is. west to Attu, south to 

 Sitka ; Kamchatka. Low water to 80 fms. 



Chiton ruber L., Syst. Nat. xii, p. 1107. LOWE, Zool. Journ. ii. 

 p. 101, t. 5, f. 2. GOULD, Invert. Mass. p. 149, f. 24; edit. Binney 

 p. 260, f. 523. FORBES & HANLEY, Hist. Moll. G. B. ii, p. 399, t. 

 59, f. 6 ; t. AA, f. 6. HANLEY, Sh. of Linn. p. 17. SOWERBY, 

 Conch. Illustr. f. 103, 104. KEEVE, Conch. Icon. f. 175. JEF- 

 FREYS, Brit. Conch, iii, p. 224 ; v, p. 199, t. 56, f. 4. Ch. cinereus 



0. FABR., Faun. Gronl. p. 423, not of authors nor of Linne. Ch. 

 minimus SPENGL., not of Gmel. Ch. Icevis LOVEN, Ind. Moll. lit. 

 Scand. p. 28, 1846, not of Mont., Forbes & Hanley, et al. Ch. 

 Icevis PENNANT (probably), Brit. Zool. (iv), iv, p. 72, t. 36, f. 3. 

 Ch. latus LEACH, Moll. Brit. p. 231. Chiton (Lepidopleurus) ruber 

 JEFFREYS, Brit. Moll, iii, p. 210. Trachydermon ruber CARPENTER, 

 Bull. Essex Inst. v, p. 153, 1873. Boreouhiton ruber BARS, Moll. 

 Reg. Arct. Norv., p. 116, t. 8, f. 4. Tr. ruber DALL, Proc. U. S. 

 Nat. Mus. 1878, p. 320 (1879). Chiton incarnatus REEVE, Conch. 

 Icon. f. 194, 1848.. 



The shell is apparently smooth, as described by Forbes and Han- 

 ley, but under a high power appears finely reticulated as observed 

 by Jeffreys. Its color is very variable, being usually marbled red 

 and whitish like Tonicella marmorea, but the valves may be uni- 

 form dark red or nearly pure white. I have one specimen with 

 the four central valves dark red and the rest white ; one valve in a 

 specimen is often dark red, while all the others are marbled. It is 

 most likely to be confounded with Tonicella marmorea and some 

 varieties of T. liueata, both of which have leathery girdles, while 

 this species can almost always be determined by its farinaceous 

 girdle, dusted with alternate red and whitish patches, the latter 

 nearly opposite the sutures. (Dall.~) 



1. PUNICEUS Couthouy. PI. 8, figs. 76, 77. 



Shell small, thin, elongated, elliptical, elevated and sharply car- 

 iiiated along the back, of a dull rose, or bright brick-red color, and 

 6 



