424 R. M. Field — Middle Ordovician of Central 



central Pennsylvania!!, and neighboring provinces. The 

 fauna of the Rodman does not occur in central New 



Nidulites favus 



Zittelella varians . . 



Receptaculites occidentalis 



Echinosphgerites aurantiurn 



Echinosphserites aurantium suecica 



Echinosphserites grandis 



Orthis disparilis 



Orthis tricenaria 



Plectorthis trentonensis 

 Glyptorthis n. sp 



Dalmanella n. sp. . . 

 Dinorthis pectinella 



sp. 



Plectambonites n. 

 Leptsena n. sp. . . 

 Leptsena charlotte. . . . 



Leptsena n. sp 



Rafinesquina alternata 



Christiania trentonensis . 



Oxoplecia n. sp 



Parastrophia hemiplicata 

 Protozyga exigua 



Cryptolithus tessellatus 



Ampyx sp 



Illsenus consimilis 



Illaenus americanus 



Illaenus angusticollis 



Pterygometopus callicephalus 

 Ceraurus pleurexanthernus . . . 



Eodman Chambersburg 

 of 

 Penn. 



X 

 X 



X 

 X 

 X 

 X 



X 

 X 



X 

 X 



X 

 X 

 X 

 X 

 X 



X 



X 

 X 

 X 

 X 



Marion 

 Penn. 



M-U 



L 



L-TJ 



L-U 

 L 

 L 

 L 



L 

 L 



L 

 L 

 L 



? 



L 



U 



L-U 



L 



L 



L T 

 L-U 

 L? 

 L 

 L 

 L 

 L 



Strasburg 

 Va. 



L-U 

 L-U 



Elsewhere 



Stones Rive 

 Stones Rive 

 and Trento] 



Middle 



Ordovician 



? 



? 



? 

 Stones Rive 

 and Trentoi 



Trenton 

 Stones Rive 

 and Trentoi 



9 



Stones Rive 



and Trentoi 



? 



Stones Rive 

 9 



Stones Rive 

 and Trentoi 



? 



? 



Trenton 

 Stones Rive 

 and Trentoi 



Trenton 



9 



Stones Rive 

 Trenton 



Stones Rive 

 Trenton 



Stones Rive 



and Trentoi 



*L stands for lower Echinosphserites zone, M for middle or Nidulites zone, and I 

 for upper Echinosphaerites zone of the Chambersburg. 



York, it does occur, however, in the Chambersburg area 

 (No. 16), the nearest outcrop to the southwest. 

 In the following table the fauna of the Rodman is com- 



