^widently different in having the shoulder grooved ; where- 

 as in that species the shoulder is acute and the suture is 

 profoundly impressed. 



IlEFEUENCE TO THE PLATE- 



Hpper figure ; front view. ^ 



Middle figure spire viewed from above. C p,^ia.r(j-cd 



Inferior figure lateral view. J 



The line represents the natural length. 



P!. :^9. 



