PLATE 39. 



P«ge 



Fig. 1-4. Merista ( = Meristella) l.«;vi8. 247 



1 a-d. Dorsal, ventral, front, and profile views of a young, very gibbous specimen of this 



species, wliich shows a small but very deep sinus on the ventral valve. 



2 o - e. Dorsal, profile, and front views of young specimens which are not very gibbous. 



S a - e. Views of young individuals, only one of which shows any evidence of a mesial sinus. 

 Sf.g, h, i, k. Dorsal, ventral, profile, and front views of larger specimens. The specimen 

 tig. 3 g presents no emargination in front, as do the others 3/- fc. 



3 /, m, n. Front, dorsal, and cardinal views of a full-grown specimen. 



3 0, p. r, s. Dorsal, profile, ventral, and front views of a larger specimen, showing a stronger 

 emargination in front, and a mesial sinus extending nearly to the beak of the ventral valve. 



3 t, u. Dorsal and profile views of a larger individual, which has no sinus or elevation upon 



the valves. It is possible that this may prove a distinct species. 



4 a. Interior of the ventral valve. 



4 ft, c, d. Casts of the ventral valve, and profile of the same. 



