PLATE 41. 
Page 
249 
1 a - t. Merista ( = Meristella) arcuata. 
1 a, b. Dorsal and cardinal vievvs of a young specimen. 
1 c, d, e,f. Dorsal, ventral, and profile views of large specimens. 
1 g, h, i, k, l. Dorsal, ventral, profile, and front views of full-grown individuals, showing the 
forms of well-preserved specimens. 
1 7 / 1 , n. Dorsal and profile views of a very gibbous form, which is uuusually extended laterally. 
1 o. Interior of a ventral valve. 
1 p. Cast of the beak of the ventral valve. 
1 t. An imperfect specimen which has been eroded at the sides, showing the internal spires. 
2 a - g. Casts of Merista ( — Meristella) : Probably of M. arcuata. 
2 a. Cast of the dorsal valve. 
2 b. Cast of the ventral valve, showing the muscular impressions and extended process which 
filled the beak of the shell. 
2 c, d. Casts of the ventral valve, showing some differences in the form of the muscular im¬ 
pressions, and the portions filling the cavity of the beak. The radiating striae are partially 
preserved on fig. 2 c. 
2 e. Cardinal view of a well-preserved cast. 
2/, g. Profile views of 2 d and 2 c respectively; the specimens 2 c, g preserving the cast of 
both valves, 2 d,f being the ventral valve only. 
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