181 UN'" iinoN m HHO1 \iHIA. 1 J7 



I. ii LKODADI ran ( topenter, D, >p. 1M. in. ligs.fji. *'<~> t 66. 

 Shell oval-tihloiig. moderately elevated, l>ack railn i mindly arched, 



<c:mvly keeled. Soiled hull', maculated an; .-. iih Uarki-h- 



brown. 



Lateral areas slight! j raised, cut \\\\<> <! to 9 low flat un''|ual 



rihlets by radiating impressed lines, the rihlets made IMU-VI n \>\ 

 cent rie wrinkles of growth ; central areas very mi nutcly pitted all 

 over, the surface being something between aquinemirial granulation, 

 and a succession of ww-like zigzags. End valves having fine radiat- 

 ing riblets cut by some cencentric growth-sulci. Mucro in front of 

 the middle, rather prominent. 



Interior blue-white ; sinus smooth ; sutural plates low, rounded ; 

 anterior valve having 15-20, central valves 2-3, posterior valve 15 

 narrow slits ; teeth rather sharp, sometimes slightly roughened ; eaves 

 short, narrow, solid. 



Girdle covered with small, solid, convex, smooth scales (fig. 66). 



Length 25, breadth 15 mill. 



Hakodadi, J 



This species, which was collected by Wm. Stimpson of the North 

 Pacific Exploring Expedition, has very much the aspect of /. / 

 co*us Old. of Australia, the sculpture of the central areas being of 

 the same zigzag character. From all species of the /. longi- 

 cymba group, however, this is distinguished by its smooth, convex 

 girdle scales, and by the plurality of slits in the side insertion-plates. 

 The above description and figures are drawn from part of the 

 original specimens. 



I. ALBRECHTI Schrenck. PL 19, figs. 70-74. 



Shell large, oval, elevated, the dorsal ridge acute ; mucro median, 

 nearly flat. Reddish maculated with darker, the interior having 

 rays of reddish-brown. 



Entire surface minutely and closely punctate; central areas with 

 about 30 lines of granules oil each side of, and parallel with, the 

 jugum ; lateral areas having in the young 4 to 6, in the adult 10 to 

 12 radiating, distantly granose riblets; the end valves having 50 

 riblets. 



Interior: posterior valve having 12, central valves ? to 3, ante- 

 rior valve about 17 slits ; teeth acute, sometimes rugose or lobed at 

 the edges, outside ; sinn< moderate, 8 to 12 dentate. 



