PLATE LX. 



(Figures 1-.!, 6-10, 13-49, SI, 53, 54^by G. B. SIMPSON'; 4, 5, 11, l'2 by K. Emmons; 49, 50, 52, 65 by K. 1'. Whitfield.) 



SUBGKNUS PUGNAX, S.-QEN. NOV. 



Page -lOi. 



PUGNAX ALTUS, ('illvill. 



Figs. 1-3. Dorsal, profile and frontal views of an average specimen ; sliowing the trihedral form and the 



character of the plication. 



Middle Devonian. >So!o7i, Iowa. 

 Figs. 4, 5. Frontal and profile views of an individual with highly elevated median fold. 

 Middle Devonian. Haokbemj Gi-ovc, Iowa. 



PUGXAX PUOXUS, Mllftill. 

 Figs. 6, 7. Dorsal and ventral views of an internal cast ; showing the form of the muscular impressions on 



the two valves. 

 Figs. 8, 9. Front views of two specimens ; showing some difference in the elevation of the median fold and, 



in figure 9, vascular markings on the sinus of the pedicle-valve. 

 Fig. 10. A profile view of the specimen represented in figures 6, 7. 



Lower Chemung group. High Point, Naples, N. Y. 



PuGNAX EATONiiFORMis, McChesiiey. 

 Figs. 11, 12. Front and profile views of the original specimen ; showing the str-ong but spar.sely plicated 

 median fold and sinus and the smooth lateral slopes. 

 Coal Measures. Qraysnille, Illinois. 



PuGNAX Gkosvenoki, Hal!. 

 Fig. 13. Ventral view of an average specimen. X 2. 



Fig. 14. Profile of another specimen ; showing the subtrihedral form. X 2. 



Figs. 15-17. Front views of three individuals; showing differences in the size of median fold and sinus and 

 in the number of plications. X 2. 



St. Louis group. Spergen Hill, Indiana. 



PuGNAX MUTATU8, Hall. 

 Figs. 18, 19. Doi'sal and profile views of an average example. 

 Fig. 20. The interior of an incomplete pedicle- valve ; showing an open delthyrium, small teeth and dental 



plates. 

 Fig. 21. A portion of the intei-ior of a, brachial valve ; showing the divided hinge-plate. 

 Fig. 22. Front view of the specimen represented in figure 18; showing the width and elevation of the fold. 

 St. Louis group. Spergen Hill, Indiana. 



PuGNAX Ottumwa, Whitf. 

 Figs. 23, 24. Dorsal and front views of a normal example ; showing the plication about the margins and the 



elevation of the median fold. 

 Fig. 25. The interior of a poi'tion of the brachial valve ; showing the broadly divided hinge-plate. X 2. 

 Fig. 26. The interior of an incomplete iiedicle-valve ; showing teeth and dental jilates. X 2. 

 St. Lonis group. Pella, Iowa. 



PuGXAX Svvalloviana, Sluimtlltl. 

 Figs. 27-29. Dorsal, profile and front views ; showing the contour and character of plication. X 2. 

 Fig. 30. Profile view of an internal cast; showing vascular sinuses on the brachial valve. X -'. 

 Figs. 31, 32. Ventral and dorsal views of a smaller shell. X 2. 



Id all of these the absence of plications over the umbonal regions is a notable featui'e. 

 Upper Coal Measures. Manhattan, Kansas. 



