PROCEEDINGS OF UNITED STATES NATIONAL -MUSEUM. 309 



Dr. Carpenter, seeing young- specimens, could not recognize the pore- 

 tufts of Gould. Shortly before liig death, however, he sent me speci- 

 mens which showed them i)laiuly; it is evidently a character in this 

 gi'ouii of very little imi)ortance. 



As regards its identity with vestita; when dry, the Xew England form 

 I)recisely resembles the figures from Sov»-erby's type-specimen in his 

 ( 'onchological Illustrations, taken from a dried specimen. lie consid- 

 ered Emcfsoiiil a s;smonym, and I fully agree T\'ith him, but have lcej)t 

 the two .separated in the foregoing synonymy for the comenience of 

 those who may doubt this. 



This si)ecies is very close to A. PallasU, but is distinguisliable by the 

 larger and laterally much more exi3anded exi)osed portions of the valves, 

 by its flatter form, and proportiouallj^ sparser and longer seta^. When 

 dry, the Vviiole form of the A'alves is visible in vestita from above, IdiC 

 the bones of a Peruvian mummy; in Pcdiasii, however, the integument 

 is so much more coriaceous and thick, that in dry specimens hardly any- 

 tliing of these outlines is visible. Midden dorf's figure, copied by 

 Cln^nu, well represents A. FaUasil when fresh. In cabinets it is rare, 

 and is not common in the field where collectors have searched for it. 



Aniicula Pallasii. 



Chiton Pallasii Midd. Bull. Acad. Sci. St. Petersb. vi, p. 117, 1847. 

 Chiton (subg. Phmtouhiton, sect. Dichachiton, subs. Syiiimetrogephyrus) raUasii 

 Jlidd. Mai. Eoss. i, p. 93, 1847; Sib. Eeise, p. 163, t. xiii, f. 1-9; t. xiv, f. 

 1-C, 1851. 

 Amicula PaUam H. & A. Ad. Geu. i, p. 481, 1854.— Chenu, i, p. 383, 1859. 

 jStimpsonicHa Pallasii Cpv. Bull. Essex lust. 1873, p. 155. 



A. t. valvarum mucrone cordilbrjui solum externe conspicua; intus 

 v. post, mopaloidea, utr. lat. unitissata, siuu caudali minore, lamina j)o- 

 stica extus rugosa hito, brevi; v. centr. 1-, v. ant. G-8-fissatis; lam. 

 acutis ex fissuris umbonem tenus sulcatis; lam. sutur. ant. modicis hand 

 separatis, sinu lato brevi; x^ost. latis, regulariter arcuatis, a siuu postico 

 lato alto separatis, (Cpr.) Limbus (zona) luxurians in pallium exteudi- 

 tur, totum animalis dorsum rotundatum obtegens, valvas obvolvens et 

 occultans, soils octo aperturis minutis, rotundatis, in linea mediana, qui- 

 bus aditus ad umbonem valvarum pat et; color squalido hitescens; epi- 

 dermis dorsalis undique versum fasciculis pilorum crinita. Lon. G7, Lat. 

 48, Alt. 21 mm. Div. 120°. 



Hah. — Okhotsk Sea, ]Midd. ; Pribilofl", Aleutian, and Shumagin Islands, 

 Dall ! .'> to 10 fathoms, very rare. Seven specimens examintnl. 



The rounded back, tough and hairy girdle with minute holes for the 

 tips of the valves, the valves themselves less transverse as a whole and 

 much less exposed than in vestita, are the characters by wliich this spe- 

 cies may be readily distinguished from the latter. My specimeus have 

 only six fissures in the anterior valve against eight in a specimen of 

 vestita of the same size. 



