12 J, Hall on Cryptonella, Centronella, Meristella, 
Valves articulating by teeth and sockets. Surface smooth o 
ark y fine concentric lines of growth, not lamellose, a8 
Sadigtact or obsolescent radiating striz, which are usually mo 
Fig. 27. Meristella nasuta = Atrypa nasuta, Conrad,—Dorsal view oung 
individual —Fig. 28, An older indivi opine F 29. Interior of the on ge ve 
Fig. 30. Cast of the ventral note Fig. 31. Dorsal view of the same species.-—Fig- 
32. Interior of the clorsal valve of M. Sala bowing | the hinge plate and median 
a ria 3. Cast of Santis valve of J. Barrisi.—Fig. $4. Cast of ventral 
. Has 
conspicuous in the east or exfoliated surfaces than on the exte 
Tior. Shell fibrous. 
The ventral os is much thickened on each side towards 
he beak, rostral cavity margined by ose 1 jental 
_* The casts of Mf. Barrisi and M. Haskinsi are obtained from solid specimens 
the and therefore have not tb: of tthe uscular 
pbc tin on Soggy weathered casts, ea A Fea ‘ 
