42 TONICELLA. 



Boreocliiton for the two forms. The Greenland and East American 

 specimens are 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 

 from 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" 

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

 grannlose. 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. 



Girdle smooth, shining, yellow or brown. 



Branchiaa 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. 

 Tonicella submarmorea Midd., DALL, Proc. U. S. Nat. Mus. 1878, 

 p. 296, t. I, f. 7 ; p. 327 ; 1. c. 1886, p. 210. Chiton insignis REEVE, 

 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. LINEATA 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 

 valve having a light triangle with a narrower dark one in the mid- 

 dle 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. Sutural 

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

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



