308 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



Amicula vestita. 



Amicula vestita Gray, P. Z. S. 1847, pp. G5, 69, 169. — H. & A. Adams, Gen. Roc. 



Moll, i, p. 480, pi. 55, f. 2, 1854.— Gray, Guide, p. 187, 1857. 

 Amicula vestita Cpr. Bull. Essex Inst. 1873, p. 155. 

 (f Far. Emersonii.) 



Chiton Emersonii Couthouy, Bost. Journ. Nat. Hist, ii, p. 83, pi. iii, f. 10, 1838. 

 Chiton Emcrsonianus Gould, Iuv. Mass. \). 151, f. 19, 1841. — Reeve, Conch. Icon, 



Mon. Chiton, pi. xi, f. 59, 1847. 

 Amicula Emersonii Gray, P. Z. S. 1847, p. 69. — H. & A. Adams, Gen. Rec. Moll. 



i, p. 481, 1854. — Gray, Guide, p. 185, 1857. — Stimpson, Smithsonian Checklist 



of East Coast Shells, 1830.— Binney's Gould, p. 234, f. 527 (bad), 1870. 

 Amicula vestita Stimpson, Shells of N. Engl. p. 29, 1851. 

 Stimpsoniella Emersonii Cpr. Bull. Essex Inst. 1873, p. 155. 



A. t. val varum parte exposita (liuic generi) majore, lata, subreni- 

 forme, antice acuta sed hand prolongate, lateribus rectangulatis, postico 

 bilobatis, sinu latiore; ar. jug. eentr. et lat. baud definitis; tota superficie 

 granulosa, supra jugum lseviori; circa marginem undique (nisi ad mu- 

 cronem in sinu postico) bicostata ; intus, v. post, typice mopaloideo, utr. 

 lat. unifissata, sinu caudali lato, breviore; v. centr. 1-, ant. G-fiss.; 

 laminis acutis, fissuris parvis, sulcis ex fissuris baud loricam tenus con- 

 tinuis; lam. sut. ant. baud separatis, sinu lato, brevi; post, minoribus 

 sed a sinu postico alto latiore omnino separatism (Cpr.) Zona tenui, 

 heviorej setulis furfuraceis et fasciculis setarum plus minusve irregu- 

 laris supra zonam exposita. Lon. 50, Lat. 35 mm. 



Ilab. — Arctic Ocean, extending southward in tbe Pacific region to 

 Hagmeister and St. Paul Islands, Bering Sea; on tbe Atlantic soutb on 

 tbe New England coast to Cape Cod; in 5-30 fatboms, mud and stones. 

 Two young specimens, not certainly of tbis species, in CO fatboms, Cap- 

 tain's Bay, Unalashka. Thirteen specimens examined. 



The "ovarian" openings, bilaterally symmetrical, are situated just be- 

 hind and, as it were, under the shadow of tbe posterior brancbia on each 

 side. They are not simple orifices, but fenestra, compsoed of two open- 

 ings somewhat oblique and linear; the anterior a little nearer the girdle 

 and a little larger than the posterior one. 



I have no doubt whatever that the original vestitw of Sowerby (from 

 Beechey's original locality I have examples) is identical with the Emer- 

 sonii of Couthouy. 



Much has been said about the presence or absence of 'pores' and 

 hair-tufts. I find from examination of a series that the young Hmcrsonii 

 is usually smooth, the large ones always setiferous. These setse arc, as 

 described by Dr. Gould, in two rows on each side, or rather six in all if 

 we count the pretty constant tufts behind the exposed apices of tbe 

 shell. These rows are (1) two behind the shell points as above; (2) two, 

 one on each side at the posterior angle of the submerged expansion of 

 the valve; (3) a series, more or less irregular, along the margin of tho 

 girdle. Beside tbis, in old ones, there are irregular tufts all over the 

 girdle, and some of the regular tufts may be missing. 



