PLATE 27. 



Page 



Fig. \ a- p. Spirifer macropleueus. 202 



1 a. A young shell in which the plications are but faintly developed. 



1 6, c. Dorsal and profile views of a specimen of medium size. 



1 rf & A. Front and cardinal views of the same. 



1 e,f, g. Dorsalj front and cardinal views of a very symmetrical form of medium size. 



1 i. Ventral valve of a specimen of larger size. 



1 fc. Ventral view of a larger individual, which is nearly of the maximum size observed. 



1 /. A cast which is somewhat crushed from the base. 



I m, n. Interior of the ventral valve, and cast of the same. 



1 0. Part of the exterior of a slightly weathered specimen, showing the extremity of the spire. 



1 p. Enlargement of the radiating strias as seen under a lens upon the surface of ordinary 

 specimens. 



