EASTMAN : CARBONIFEROUS SHARKS. 99 



PLATE 5. 



Fig. 1. Ciena canthus spectabilis St. J. a.ndW. Kinderhook Limestone ; Mississippi 

 Valley. Left lateral aspect of spine referred to the second dorsal fin. 

 Original preserved in the U. S. National Museum. (Cat. No. 4845). 

 X\. 



Fig. 2. Ctenacanthns hnginodosus, sp. nov. Kinderhook Limestone ; Mississippi 

 Valley. Basal portion of spine referred to the first dorsal fin. Original 

 preserved in the U. S. National :\Iuseum. (Cat. No. 3393). X \. 



Fig. 3. Acanthodes marshi (?), sp. nov. Coal Measures; Mazon Creek, Illinois. 

 Fin belonging presumably to a young individual of same species as 

 shown in Plate 6, Figure 3, with attached spine and calcified fin-mem- 

 brane. Original preserved in Yale Museum. X \. 



PLATE 6. 



Fig. 1. Ctenacanthns lucasi, sp. nov. Kinderhook Limestone ; Mississippi Valley. 

 Basal portion of spine referrer^ to the first dorsal fin. Original pre- 

 served in the U. S. National Museum. (Cat. No. 4844). X {■ 



Fig. 2. Ctenacanthns decussatus, sp. nov. Kinderhook Limestone ; Mississippi 

 Valley. Proximal portion of spine referred to the first dorsal fin. 

 Original preserved in the U. S. National Museum. (Cat. No. 4846). 



X^ 



1- 



Fig. 3. Acanthodes marshi, sp. nov. Coal Measures ; Mazon Creek, Illinois. Im- 

 pression of nearly complete pectoral fin preserved in counterpart, show- 

 ing fin-spine and actinotrichia, but without supporting basal element. 

 Original in Yale University Museum. X {. 



PLATE 7. 



Fig. 1. Acanthodes marshi, s^.noY. Coal Measures ; Mazon Creek, Illinois. Nod- 

 ule containing a portion of the dermal covering (shagreen), the granules 

 of which are preserved in their natural arrangement, and present the 

 structure sliown in Fig. 2. Original in Yale University Museum. X \. 



Fig. 2. Acanthodes marshi, sp. nov. Enlarged drawing of some of the shagreen 

 granules from the type-specimen shown in Fig. 1. X f. 



Fig. 3. Ctenacanthns solidits, sp. nov. Kinderhook Limestone ; Mississippi Valley. 

 Proximal portion of spine referred to the second dorsal fin. Original 

 preserved in the U. S. National Museum. (Cat. No. 4843). X x- 



