PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 327 



The gill-rows extend forward two-thkds the length of the foot. They 

 contam about twenty-seven branchiiie on each side, fhe mantle-edge is 

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

 The edge of the muzzle is marginated all aroundj and draAvu into flails 

 at the posterior corners. 



Tonicella submarmorea. 



Chiton siibmarmoreus Midd. Bull. Acad. Sci. St. Petersburg, i\', No. 8, 1846; 

 MaL Ross, i, p. 98, 1847; lb. Sib. Eeise, p. 178, pi. xiv, f. 7-10, xv, £ 7-8, 

 1851. 

 Cliiton insignia Reeve, Conch. Icon. Mon. Chiton, pi. xxii, No. 149, f. 148, 1847. 



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

 maculis tlammulisque sed rufis, sed albis picta; tegmentum zoniB la3vius- 

 culum, nitidulum, iiavum aut fuscum pictum. 



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

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

 Washington Territory. 



In the description of this form, JMiddendorf, in disting-uishing it from 

 T. marmorea, seemed to overlook its relations to T. Umata^ 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. linc- 

 ata in occasional specimens 5 though these may be due to hybridization. 

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

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

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

 absent. The specimen was a male, and the structure of the spermsac 

 recalled that of Acmcca. Some of these differences maybe sexual; at 

 all events, the subject requires investigation irom Uvmg specimens. 



Tonicella saccharma. 



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



T. t. parva, oblouga, tota superficie saccharina rufo et albescente picta; 

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

 sanguinosis, aeque quincuncialiter lente reticulata; v. ant. 10-11-, v. 

 j)ost. 8-10-, V. centr. 1-flssata ; dent, parvis, spongiosis ; sinu parvo ; sub- 

 grundis spongiosis, mediocris; zona coriacea ut in Toniccllcc aliis. 

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



Hal). — Aleutian and Shumagin Islands ; Kyska, Unalashka, and Koni- 

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

 Seven specimens examined. 



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

 which the microscoi^ic reticulation is barely i)erceptible. 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 i:>ubescent, 



