PLATE LXIV 



PAGE 



Fig. 1. CAMABOTCECHIA (PLETHORHYXCHA) SPECIOSA VAR. RAMSAYI (Hall). 358 

 Dorsal view of the type specimen. Oriskany formation, Ridgely mem- 

 ber, Cumberland. (After Hall.) 



Figs. 2, 3. CAMAROTCECHIA ( PLETHORHYXCHA ) BARRANDII (Hall) 359 



2. Internal cast of ventral valve. 



3. Anterior view of a very gibbous specimen. 



Oriskany formation, New York. 



Figs. 4, 5. CAMAROTCECHIA (PLETHORHYNCHA) BARRAXDII VAR. FITCHANA 



(Hall) 359 



Dorsal and side views of internal cast. Oriskany formation, New 

 York. 



Fig. 6. CAMAROTCECHIA (PLETHORHYXCHA) PLEIOPLEURA (Conrad) 360 



Dorsal valve. The drawing is much restored on the left. Oriskany 

 formation, Ridgely member, Cumberland. 



Figs. 7-10. UXCIXULUS VELLICATUS (Hall) 362 



7-9. Dorsal, cardinal, and anterior views. 



10. Plications of fold and sinus enlarged to show their linear median 

 furrows and zigzag lines of growth. 

 New Scotland formation, New York. 



Figs. 11, 12. UNCINULUS ABRUPTUS (Hall) 363 



Dorsal and ventral views. New Scotland formation, New York. 



Figs. 13-15. UNCIXULUS GLOBULUS Schuchert 364 



13, 14. Dorsal and side views. 



15. Anterior view of a larger specimen. 



New Scotland formation, New York. 



Figs. 16, 17. UXCIXULUS NUCLEOLATUS (Hall) 365 



Ventral and side views. Helderberg formation, Keyser member, 

 Keyser, W. Va. 



Figs. 18-20. UXCIXULUS NUCLEOLATUS VAR. AXGULATUS Maynard n. var. ... 366 

 Side, ventral, and dorsal views of type specimen. Helderberg forma- 

 tion, Keyser member, Cumberland. 



55 



