PLATE 64. 



P.ge 



Fig. 1-5. Plattceras plicatum. 334 



1. A young specimen in which no plications are developed. 



2. A more slender specimen in which the plications are strongly marked. 



3 & 4. A larger individual, in which the plications arc but moderately developed. 



5. A large specimen which is compressed, the view shownig a width greater than the natural 

 width of the shell. 



Fig. G & 10. Plattceras elonoatum. 335 



6. A young specimen of this species. 



10. A large individual from which the extremity of the apex is broken, and the shell partially 

 exfoliated from the lower part. 



Fig. 7, 8, 9. Plattceras pyramtdatum. 336 



7 & 8. Two views of the same specimen. 

 9. View of a smaller specimen. 



