PLATE 44. 



Fjg. 1-5. Meeista ( = Meristella? ) trinceps. ^J 



1 a, fc; 2 a, 6, and 8 o, 6, c. Ventral, dorsal, profile, and front views oi young individnalH, 

 where the sinus is scarcely defined beyond the front, and there is no niesial fold on the 

 dorsal valve. These specimens preserve so much tlie character of Meruia lavis, that 1 

 have some hesitation in placing them under this species; but they are more extended in 

 front, and the outline less regularly curved . 



A a,b, c,d. Dorsal, ventral, profile and front views, in which the characteristic features of the 

 species are fully developed . 



■* «)/> St *• Views of a specimen of extremely large size, showing the broad and shallow 

 mesial sinus, and the linguiform extension in front, which is bent abruptly upwards. 



6 o, b, c, d. Views of a specimen having the form of the two preceding, but with a narrower 

 and more angular sinus. 



Fig. 6 a, b, c, d. Merista meeki. 252 



6 o, 6. Ventral and dorsal views of this species. 

 6 f , d. Profile and front views of the same. 



