IL' TONICELI A. 



Boreochiton for the two forms. The Greenland and East American 

 s|M<im.n> arc more elevated and generally larger than the British 

 form, which might retain the varietal name latus Lowe. 



Middendorff found the number of slits variable in his specimens 

 fn>m the White Sea and the Arctic coast of Russian Lapland, the 

 anterior valve having 5 to 7, posterior valve 6 to 9 slits. 



T. SUBMARMOREA Middendorff. PI. 10, figs. 16-24. 



Shell oval, rather depressed, rather smooth and shining, the entire 



sui face seen under a lens to be very minutely, regularly and closely 



///. Lateral areas scarcely distinct, slightly swollen. Color 



rosy or yellowish-white, closely painted with spots and flames of red. 



Interior rose colored ; terminal valves each with five slits. 



< iirdle smooth, shining, yellow or brown. 



Uranchia' median, consisting of about 24 plumes. 



Length 38, breadth 24, alt. 12-13 mill. 



Japan, Okhotsk Sea ; Aleutian Is. to Sitka and Fuca Strait. 



C. submarmoreus MIDD., Bull. Acad. Sci. St. Petersb. iv, 1846 ; 



Mai. Ross, i, p. 98 ; Sib. Reise. p. 178, t. 14, f. 7-10 ; t. 15, f. 7, 8. 



Tonlrcll'i xnbmarmorea Midd., DALL, Proc. U. S. Nat. Mus. 1878, 



p. 296, t. I, f. 7 ; p. 327 ; I. c. 1886, p. 210. Chiton insignis REKVK, 



Conch. Icon. t. 22 ? f. 148, 1847. 



This species is readily distinguished from T. lineata by its micro- 

 scopic granulation ; from T. marmorea by its more depressed shell, 

 different color-pattern, etc. 



T. MM: A i A Wood. PI. 11, figs. 25-28. 



Shell oblong, rather low, roundly arched or subcarinated. Sur- 

 face smooth, shining, ground color light reddish. End valves con- 

 centrically marked with black-brown lines bordered above with 

 white, intermediate valves having similarly colored longitudi- 

 nal lines, sloping obliquely backward, the ridge or jugum of each 

 valv. havinir a light triangle with a narrower dark one in the mid- 

 dl- on some valves. Occasionally some valves are wholly dark 

 brown, unmarked. 



Lateral areas scarcely raised ; umbo of posterior valve in front 

 of the middle. 



Interior white, more or less tinged with rose color. Sutnral 

 plates broad, rounded ; sinus deep and angular. Anterior valve 

 with 8-10, median 1, posterior valve 8-10 slits. Teeth short, espe- 



