44 TONICELI-A. 



T. SACCH A i : i N A I )al 1 . Unfigured. 



Shell small, oblong, the entire surface painted with lustrous red 

 and whitish. Urabo subcentral, inconspicuous. Lateral areas 

 indistinctly raiaed ; dorsal area blood colored, reticulated in quin- 

 cunx. Anterior valve having 10-11, posterior 8-10, median 1 

 slit. Teeth small, spongy ; sinus small ; eaves spongy, moderate, 

 (irdle leathery, (iills median. Length 6, breadth 4 mill. 



i ami Shumagin Is.; Kyskn, Utialashka, and Koniu*hi, 

 8 fa&, on stones; St. Paul, Pribiloff Is., 15 fms. 



i it-ell n miccharina DALL, Proc. U. S. Nat. Mus. 1878, pp. 2, 

 827. 



This interesting little species has the luster of rock-candy, through 

 which the microscopic reticulation is barely perceptible. It is 

 marked in all the specimens obtained, by the red wine colored dor- 

 sal areas contrasted with a waxy white color of the lateral areas, 

 rendering its recognition easy. The girdle is dark, leathery, nar- 

 row, slightly pubescent, and furnished at its extreme margin with a 

 fringe of fine spiny hairs or spicules, as in T. marmorea. 



T. SITKKNSIS Middendorff. PL 11, figs. 29, 30, 31. 



Shell depressed, smooth, the lateral areas indistinct, under a lens 

 seen to be sparsely granulose ; reddish. Anterior valve having 8, 

 1". -tenor 10, central 1 slit. Gills posterior. 



Length 10, width 6 mill. ; divergence 130. 



Sitka. 



C. sitketms MIDD., Bull. Acad. Sci. St. Petersb. vi, p. 121, 1846 ; 

 Mai. Ross, i, p. 112, t. 13, f. 1, 2. Not C. sitkensis Keeve, 1847. 



I > scribed from a single specimen, and not found by later collec- 

 Middendorff 's figures and description do not agree upon sev- 

 t-ral points. The anterior teeth are figured as grooved outside, a 

 character also seen in T. lineata. 



Subgenus CYANOPLAX Pilsbry, 1892. 



Valves resembling those of Ischnochiton, but having the teeth 

 MMiit. obtuse, crenulated or hi- or trilobed at their tips; and the 

 :!'. [">i,j\ -. (iirdle leathery, miniftely papilloBC. (Jills extend- 

 ing to the anterior end of the foot. 



I)it}!-r> from ( '/mtojtfeura in the spongy eaves and papillose, not 

 Jfiini L r ir<llc; from ToniceUa in the long gills, different girdle, 

 stumpy, bilobed anterior teeth, etc. It might be considered a 



