PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 327 



The gill-1'OAvs extend forward two-tliirds the leugth of the foot. They 

 contain about twenty-seven branchiip on each side. The mantle-edge is 

 very narrow, hardly distinguishable around the head. There is no veO. 

 The edge of the muzzle is marginated all around, and drawn into flaps 

 at the posterior corners. 



Tonicella submarmorea. 



Chiton suhnarmoreus Midd. Bull. Acad. Sci. St. Petersburg, iv, No. 8, 1846; 



Mai. Ross, i, p. 98, 1847; lb. Sib. Reise, p. 178, pi. xiv, f. 7-10, xv, f. 7-8, 



1851. 

 Chiton insignia Reeve, Concb. Icon. Mou. Chiton, pi. xxii, No. 149, f. 148, 1847, 



T. t. ut in forma prsecedente, sed testa externa ex rosea flavoque alba, 

 maculis flammulisque sed rufis, sed albis picta; tegmentum zonoe Inevius- 

 culum, nitidulum, flavum aut fuscum pictuni. 



Hah. — Japan and the Okhotsk Sea, Aleutian Islands to Sitka and 

 Puca Strait. It has not been found north of the Aleutians or south of 

 Washington Territory. 



In the description of this form, Middendorf, in distinguishing it from 

 T. marmorea, seemed to overlook its relations to T. Imeata, from which, 

 for some time, I was indisposed to specifically separate it. The peculiar 

 color of the valves is reproduced sporadically on some valves of T. line- 

 ata in occasional specimens; though these may be due to hybridization. 

 The dentition, elsewhere figured, indicates, however, that the two fonns 

 are specifically distinct. The soft parts are very similar to those of T. 

 marmorea in every respect except that the openings near the anus were 

 absent. The specimen was a male, and the structiu'e of the spermsac 

 recalled that of Acmwa. Some of these differences may be sexual; at 

 all events, the subject requires investigation from living specimens. 



Tonicella saccharina. 



Tonicella saccharina Dall, Proc. Nat. Mus. p. 2, Jan. 1878. 



T. t. parva, oblonga, tota superficie saccharina rufo et albescente pictii; 

 mucrone submediano, inconspicuo; ar. lat. inconspicue elevatis, ar. dors, 

 sanguinosis, ieque quiucuncialiter lente reticulata; v. ant. 10-11-, v. 

 post. 8-10-, V. centr. 1-fissata; dent, parvis, spongiosis ; sinuparvo; sub- 

 grundis spongiosis, mediocris; zona coriacea ut in Tonicellcc aUis. 

 Branchiis mediis. Lon. C.5, Lat. 4 ram. 



Hah. — Aleutian and Shumagin Islands; Kyska, Uualashka, and Koni- 

 ushi, 3 to 13 fathoms on stones! St' Paul. Pribiloff Ids., 15 fathoms. 

 Seven specimens examined. 



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

 which the microscopic reticulation is barely perceptible. It is marked, 

 in all the specimens obtained, by the red wine colored dorsal areas con- 

 trasted with a waxy white color of the lateral areas, rendering its rec- 

 ognition easy. The girdle is dark, leathery, narrow, slightly pubescent, 



