PLATE 24 

 Plectonotus cf. derbyi Clarke 



Page 98 



1-11 Various views of this shell showing the essential characters as pre- 

 served on internal and external casts. Figures 1, 2, 4, 7,8 are 

 enlarged, x 2 

 Locality. Presque Isle stream 



Pterinea edmundi Clarke 



Pase 103 



12-14 Left valves showing some variation in form 



1 5 A right valve 



16, 17 Other left valves, 17 somewhat angulated by compression along the 



crescence ridge 

 18 A very oblique, probably compressed right valve 

 Locality. Edmunds Hill 



Pterinea edmundi var. subrecta Clarke 



Page 104 



19, 20 Right and left valves of this variety 

 Locality. Edmunds Hill 



Pterinea radialis Clarke 



(See plates 13, 14) 

 Page 103 



21, 23. 24 Left valves 



22 Umbonal portion of internal cast of right valve, x 2 

 Locality. Presque Isle stream 



Pterinopecten aroostooki Clarke 



Page 1 : 



25-28 Left valves showing form and sculpture 

 Locality. Edmunds Hill 



Pterinea sp. 

 Type of P. laevis Goldfuss 



P ^e 104 



29. 30. 33 Internal casts of shells apparently without radial sculpture 

 Localities. Edmunds Hill and Presque Isle stream 



214 



