PLATE XXIV 



PAGE 



OLENELLUS THOMPSONI (Hall) 339 



A large, almost entire individual of this characteristic trilobite with 



the third segment unusually prolonged. (After Walcott.) 

 Fragments of the free checks or of the segments are the portions most 

 frequently found in the Antietam Sandstone of Maryland. 

 Cambrian. Georgia slate, Parker's quarry, Georgia, Vermont. 



374 



