308 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



Amicula vestita. 



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



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

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

 (? Far. Emersonii. ) 



Chiton Emcrmnii Coutliouy, Bost. Journ. Nat. Hist. 11, p. 83, pi. iii, f. 10, 1838. 

 Chiton Emersonianus Gould, Inv. Mass. p. 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.— Binuey's Gould, p. 2J4, f. 527 (bad), 1870. 

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

 Stimpsoniella Emersonii C])y. Bull. Essex Inst. 1873, p. 155. 



A. t. valvarum parte exposita (huic generi) majore, lata, subreni- 

 forme, antice acuta sed hand prolongata, lateribus rectangulatis, postice 

 bilobatis, sinu latiore; ar. jng. ceiitr. et lat. hand deflnitis; tota superflcie 

 gramdosA, supra jugum Ireviori; circa marginem uudique (nisi ad mu- 

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

 lat. nnifissata, sinn caudali lato, breviorej v. centr. 1-, ant. 6-fiss.; 

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

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

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

 laiviore; setulis furfuraceis et fascicuMs setarum plus minusve irregu- 

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



Hab. — Arctic Ocean, extending soutbward in the Pacific region to 

 Hagmeister and St. Paul Islands, Bering Sea; on the Atlantic south on 

 the New England coast to Cape Cod ; in 5-30 fathoms, miid and stones. 

 Two young specimens, not certainly of this species, in GO fathoms. Cap- 

 tain's Bay, Unalashka. Thiiteen specimens examined. 



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

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

 side. They are not simple orifices, but fenestrte, 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 vestitus 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 Emersonii 

 is usually smooth, the large ones always setiferous. These setae are, 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 the 

 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 the 

 girdle. Beside this, in old ones, there are iiTCgular tufts all over the 

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



