Ill] 



ARTHROSTIGMA 



27 



Fig. 8. Arthrostigmagracile,'Da,wson, 

 from the Lower Old Red Sandstone 

 of Scotland. (Nat. size.) After Kid- 

 ston (1893). 



Fig. 9. Arthrostigma gracile, Dawson, 

 from the Lower Devonian of Rorageii, 

 Norway. After Halle (1916). 



