MOP ALIA. 301 



acter or quite like that of hindsii. 



M. MIDDENDORFFII Schreuck. PI. 62, figs. 88, 89, 90, 91, 92. 



Shell elevated. Coloration : a broad whitish area along the mid- 

 dle, with transverse flammules and lines of red-brown on the ridge ; 

 at the sides concentrically and longitudinally painted with red- 

 brown and whitish. 



Median valves having the apex indistinct, the lateral areas dis- 

 tinct. Entire surface radially closely pitted, the pits very distinct 

 over the whole of the central areas, and in the middle of the lateral 

 areas, but obsolete on the front and back edges of the latter. 

 Anterior valve having 8 radiating riblets. Posterior valve slightly 

 emarginate behind. 



Interior roseate in the middle ; lateral slits distinct ; sinus shal- 

 low. Anterior valve having 8, central 1, posterior two slits. 



Girdle of moderate width, brown-red, setose, the setae irregularly 

 and sparsely scattered, whitish, and about 3 mill, in length. 

 Branchiae median, with about 36 branchial lamellae. 



Length 14 mill. ; divergence about 115. 



Bay of Castries in 25 ft. 



Chiton middendorffii SCHRENCK, Bull, de PAcad. des Sci. St. 

 Petersb. iv, p. 408 ; Mel. Biol. iv, p. 89 ; Reisen und Forsch. in 

 Amur-Lande, ii, Zool., p. 278, t. 12, f. 1-8 (1867). 



A single specimen of this species was dredged by Schrenck, from 

 whose account the above description is compiled. The sculpture 

 strongly reminds one of some forms of Mopalia lignosa Gld., but the 

 coloring differs markedly, and the habitats of the two are widely 

 sundered. 



M. IMPORCATA Carpenter. PL 62, fig. 98. 



Shell small, oblong, strongly elevated and acutely carinated, the 

 side-slopes straight. Buff-white, slightly stained with rust-brown. 



The median valves are acute at the umbo, but there is no project- 

 ing beak; lateral areas bounded by a strongly elevated, narrow, 

 crenulated diagonal rib, and having a wider rib at the sutural mar- 

 gin, also crenulated, thus denticulating the suture ; the space 

 between the two lateral ribs being finely corrugated-granose. Cen- 

 tral areas sculptured with strong, curved longitudinal ribs, which 

 converge forward somewhat, toward the median keel ; the intervals 

 between these ribs being closely and finely latticed across by 



