44 TONICELLA. 



T. SACCHARINA Dall. Unfyured. 



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

 and whitish. Urabo subcentral, inconspicuous. Lateral areas 

 indistinctly raised ; 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. 

 Girdle leathery. Gills median. Length 6J, breadth 4 mill. 



Aleutian and Shumagin Is. ; Kyskn, Unalashka, and Koniuzhi, 

 3-13 fms., on stones; St. Paul, Pribiloff Is., 15 fms. 



Tonicella saccharina DALL, Proc. U. S. Nat. Mus. 1878, pp. 2, 

 327. 



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. SITKENSIS Middendorff. PI. 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, 

 posterior 10, central 1 slit. Gills posterior. 



Length 10, width 6 mill. ; divergence 130. 



Sitka. 



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

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



Described from a single specimen, and not found by later collec- 

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

 eral 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 

 stout, obtuse, crenulated or bi- or trilobed at their tips; and the 

 eaves spongy. Girdle leathery, minutely papillose. Gills extend- 

 ing to the anterior end of the foot. 



Differs from Chcetopleura in the spongy eaves and papillose, not 

 hairy girdle ; from Tonicella in the long gills, different girdle, 

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



