lg(3 NATUEAL HISTORY BULLETIN 



Cretaceous, and Jurassic, and are even present in the Silurian." 

 (Zittel, Handhuch der Paldoneologie, Vol. 1, part 1, p. 143.) 



The presence of the borings of this little sponge in the brachio- 

 pod shells Avas first pointed out by Dr. Calvin, and whatever of 

 merit this original description ma,y have is greatly due to his 

 valuable suggestions and kind assistance. 



Locality and position: Collected by the writer in the Lime 

 Creek shales, Upper Devonian series at Hackberry Grove, Iowa. 



