I'LATK IV 1— Continued. 

 PhOLIDOI'S SUBTRUNC'ATA, ILlll. 



Fig. 19. The exteiior of au individual ; sliowing the slightly flattened iio.sterior slope and faint median 

 angulation. X 4. 



Hudson River group. Lorraine, N. Y. 



PlIOLIDOPS OVALIS, Hull. 

 Fig. 20. The external sui'face ; showing the characteristic outline and .subceritral apex. X 0. 

 Niagara group. WaMrmi, Indiana. 



PhOLIDOI'S .SQUA.MIFORMl5i. Hull. 



Fig. 21. The interior of a large ventral (() valve ; showing the character of the muscular ai-ea, the median, 

 anterioi' adductoi', lobed posterior aflductor, and jiai-ietal impi-essions. X ». 

 Niagara grouj]. Hamilton,, Ontario. 



Pholidops ovata, Hull. 



Fig. 22. An internal cast of a dorsal (0 valve ; showing the shaj'ply defined antei-ior and po.«tenor ad- 



ductoi'S, and the parietal scar. X I). 

 Fig. 23. The intorioi- of the opposite valve ; showing the relatively small size of the muscular area. X 0. 

 Lower Helderberg group. Near Clarksville, N. T. 



Pholidop.s arenakia, Hull. 



Pig. 24. An internal cast of a dorsal (i) valve. Fi-oni the oiiginal specimen. X 2. 

 Oriskany sandstone. Kno.c, N. Y. 



Pholidops areolata. Hull. 



Fig. 25. An internal cast of tlie ventral (() valve. X 3. 



Schoharie grit. Near Clarksville, JY. Y. 

 Fig. 26. An internal cast of the opposite valve. X 3. 



Schoharie grit. Knox, N. Y. 



Pholidop.s patina, sp. iiov. 



Fig. 27. The exterior of a valve ; showing the laraellose growth-lines, crossed by tine, int«iTupted, radiat- 

 ing sti'iiE. Drawn from a gutta-percha cast of a natural mould in decomposed chert. X 4. 

 ■ Fig. 28. The interioi- of a dorsal (?) valve. Fi'om a gutta-percha cast. X 4. 

 Fig. 29. The interior of the ojiposite valve. X 4. 



Coi-niferous limestone. De Cewville, Ontario. 



Pholidops calceola, sp. nov. 



Fig. 30. The interior of a dorsal (?) valve ; showing- ihe terminal beak and snbapical area, and the chai-actei- 

 of the niusculai' impressions. X 12. 



Corniferous limestone. Falls of the Ohio. 



Pholidops Hamiltoni^e, Hull. 



Fig. 31. The exterior of the sliell. X 4. 



Fig. 32. Profile of the same specimen showing the valves in conjunction. X 4. 



Hamilton group. Western New York. 

 Fig. 33. The intei-ior of a ventral (?) valve; showing the character of the mu.'scular impressions. X 8. 

 Fig. 34. The intei-ior of the opposite valve ; showing the muscular and parietal scai-s. X 4. 



Hamilton group. Canandaigua Lake, N. Y. 



Pholidops linguloides, Hull (?). 



Fig. 35. The interior of a dorsal (?) valve ; showing the tei-minal and slightly deflected beak, the subapical 

 area, and the character of the muscular scars. X 2. 

 Hamilton group. Eighteen Mile Creek, N. Y. 



Pholidops oblata, Hull. 



Fig-. 36. An internal cast of the doi-sal (?) valve, with two deep anter-ior adductor scars, the posterior ad- 

 ductors being very faintly developed, as in the preceding figure. This and figure 35 may 

 represent the same species. X 4. 



Hamilton group. Cartei-'s Mills, N. Y. 



Pholidops, conipure P. Hamiltoni.e. 



Fi.ti- 37. The exterior of the shell ; showing the form and outline. X 6. 

 Bedfonl sh:des. Bedford. Ohio. 



