308 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



Amicula vestita. 



Amicnla vcsiita Gray, P. Z. S. 1847, pp. G5, 69, 169.— II. & A. Adams, Gen. Eoc. 



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

 Amicula vcsiita Cpr. Bull. Essex lust. 1873, p. 1.55. 



(f Far. Emersonii.) 



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



Chiton Umersonianiis Gould, luv. Mass. p. 151, f. 19, 1841. — lieeve, Couch. Icon. 

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



Jmicula Emersonii Gray, P. Z. S. 1347, p. 69.— H. & A. Adams, Gen. Rcc. Moll. 

 i, p. 481, 18.54. — Gray, Guide, p. 185, 18.57. — Stimpson, Smithsonian Checklist 

 of East Coast Shclis, 1830.— Binuey's Gould, p. 254, f. .527 (bad), 1870. 



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



titimjisoniella Emersonii Cpr. Bull. Essex lust. 1873, p. 155, 



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

 forme, antice acuta sed baud prolongata, lateribus rectangulatis, j)ostico 

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

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

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

 lat. unitissata, sinu caudali lato, breviore; \. centr, 1-, ant. G-Hss.; 

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

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

 sed ii sinu postico alto latiore omnino separatis; {Cpr.) Zona tenui, 

 laiviore; setulis furfuraceis et fasciculis setarum plus minusve irregu- 

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



HaJ). — Arctic Ocean, extending soutbward in tbe Pacific region to 

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

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

 Two young specimens, not certainly of tbis species, in 60 fatboms, Cap- 

 tain's Bay, Unalasbka. Tbirteen specimens examined. 



Tbe '^ ovarian" openings, bilaterally symmetrical, are situated just be- 

 bind and, as it were, under tbe sbadow of tbe posterior brancbia on eacli 

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

 ings s^mewbat oblique and linear; tbe anterior a bttle nearer tbe girdle 

 and a little larger tban tbe posterior one. 



I bave no doubt wbatever tbat tbe original restitus of Sowerby (from 

 Beecbey's origbial locality I bave examples) is identical witli tbe Emcr- 

 aonii of Couthouy. 



Mucb bas been said about tbe i)resence or absence of 'pores' and 

 bair-tufts. I find from examination of a series tbat tbe young Emersonii 

 is usually smootb, tbe large ones always setiferous. Tbese seta; are, as 

 described by Br. Gould, in two rows on eacb side, or ratber six in all if 

 we count tbe pretty constant tufts bebind tlie 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 the 

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

 girdle, and some of the regidar tufts may be missing. • 



