50 



Annals of the Carnegie Museum. 



Explanation of Plate VI. 



Fig. I 

 Fig. 2 

 Fig. 3 

 Fig. 4 

 Fig. 5 

 Fig. 6 

 Fig. 7 



Fig. 8. 

 Fig. 9. 

 Fig. 10. 

 Fig. II. 



Fig. 12. 



Fig. 13 



Spirifer whitneyi Hall, var. monticola. X i. No. 174a. 

 Spirifer whitneyi Hall, var. monticola. X i. No. 1746. 

 Spirifer whitneyi Hall, var. monticola. X i. No. 174c. 

 Spirifer whitneyi Hall, var. monticola. X i. No. 174^. 

 Spit if er whitneyi Hall, var. monticola. X i. No. 174c. 

 Spirifer whitneyi Hall, var. monticola. X i. No. 174/. 

 Spirifer whitneyi Hall, var. monticola. X i. No. I74g. 

 (Figs. I to 7 show variations from a long, narrow form to a short wide 



form, and also in height of area and length of hinge-line.) 

 Spirifer whitneyi Hall. X 2. 

 Spirifer whitneyi Hall. (Top view of specimen shown in Fig. 8.) X 2. 



Spirifer whitneyi Hall. Lime Creek, Iowa. X 2. 



Spirifer whitneyi Hall. Lime Creek, Iowa. (Top view of specimen 



shown in Fig. 10.) X 2. 



Spirifer raymondi Haynes. Three Forks, Montana. (Ventral valve 



of extreme mucronate type.) X 2. 

 Spirifer raymondi Haynes. Three Forks, Montana. (Exfoliated 



ventral valve, showing slight fold in sinus.) X 2. 



