Fig. 27. Meristella nasuta—Atrypa nasuta, Conrad. Dorsal 

 view of a young individual. 

 Fig. 28. An older individual. 

 Fig. 29. Interior of the ventral valve. 

 Fig. 30. Cast of the ventral valve. 



Fig. 31. Fig. 32. 



Fig. 31. Dorsal view of the same species. 

 Fig. 32. Interior of the dorsal valve of M. arcuata, show 

 iug the hinge plate and median septum. 



