4 March, Morphogenesis of certain Pelecypoda. 



The absence of this bend in the later-formed Hnes may 

 be due to the fact that the divergence of the radials 

 decreases as full growth is reached. 



Fig. za. 



Showins: bendine in diagonals due to divergence of radii. 



Fig. lb. 



Showing straight diagonals where 

 the radials are parallel. 



Showing the cause of bending where 

 the radials diverge. 



Fig 2>d. 



Showing bending due to divergence on an actual specimen. 



Naturally this curve is better developed in elongated 

 forms, as in them divergence is greater, as the difference 

 of length in early and late stages is more marked. 



