44 AMICULA. 



Girdle thin, smooth ; adults generally having more or less devel- 

 oped, but always sparsely scattered, small bunches of hairs. 



Length 50, breadth 35 mill. 



Arctic Ocean, extending southward in the Pacific region to Hag- 

 meister and St. Paul Islands, Bering Sea; in the Atlantic to Cape 

 Cod, Massachusetts, in 5-30 fins., mud and stones. 



Chiton vestitus BROD. & SOWB., Zool. Journ. iv, p. 368 (1829) ;. 

 Conch. Illustr., f. 128, 128a; Zool. Beechey's Voy., p. 150, t. 41, f. 

 l4.Amicula vestita GRAY, P. Z. S. 1847, pp. 65, 69, 169. H. & 

 A. AD., Gen. Rec. Moll, i, p. 480 ; iii, t. 55, f. 2. STIMP., Sh. of N. 

 Engl., p. 29. CPR., Bull. Essex Inst. 1873, p. 155. DALL, Proc. 

 U.S.Nat. Mus/1878, p. 307; p. 299, f. 43 (dentition). Chiton 

 emersonii COUTHOUY, Bost. Journ, Nat. Hist, ii, p. 83, t. 3, f. 10 

 (1838). Amicula emersonii GRAY, P. Z. S. 1847, p. 69. BINNEY'S 

 edit, of GOULD, Invertebrata of Mass., p. 264, f. 527. Chiton emer- 

 sonianus GOULD, Inv. Mass., p. 151, f. 19. REEVE, Conch. Icon., 

 t. 11, f. 62. Stimpsoniella emersonii CPR., Bull. Essex Inst. 1873, p. 

 155; Ann. Mag. N. H. (4), xiii, p. 122 (1874). Chiton amiculatus 

 REEVE, Conch. Icon., t. 11, f. 59, not C. amiculatus Pallas. 



The relations existing between vestitus, emersonii and pallasii have 

 been clearly stated by Dall, who writes as follows : " 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 setse 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 irre- 

 gular tufts all over the girdle, and some of the regular tufts may be 

 missing." 



" This species is very close to A. pallasii, but is distinguishable by 

 the larger and laterally much more expanded exposed portions of 

 the valves, by its flatter form, and proportionally sparser and longer 

 setee. When dry, the whole form of the valves is visible in vestita 

 from above, like the bones of a Peruvian mummy ; in pallasii, how- 

 ever, the integument is so much more coriaceous and thick, that in 

 dry specimens hardly anything of these outlines is visible." 



