101 



BUTH. 





Buthotrephis gracilis, var. crassa. Hall, Pal. N. Y. Vol. 



2, 1881, pi. 5, f. 

 oa,b,c. There 

 seems to be 

 no line ot spe- 

 cific distinc- 

 tion between 

 the slender 

 forms in shale 

 and the coars- 

 er forms on 

 sandstone. 

 Clinton^ V a. 



Ha.fl. Pal. NX 







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I 



I I 



iiil 



wM/fr^^^ }w$m'^ M^^^h'H- 



^Jjiithotrephis Grantii, iw^cniiiDo Al 

 ,fi om Uio Siluiian, Canada. 



iHliJJik 



'ii^riiji'i^fi/U,f\ 



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