PLATE LXXI— Continued. 



Genus PENTAMERELLA, Hall. 



Page 241. 



Pentamekella arata, Conrad. 



Fign. 21, 93. Long:itudinal profiles of pedicle-valves ; showing the spondyliura and the variation in the 



development of the supporting septum. 

 Fig. 23. The interior of the pedicle-valve viewed from in front ; showing the spondylium and its support- 

 ing septum and the ovarian markings over the surface of the valve beneath the spondylium. 

 Corniferous limestone. Near Junction. City, Kentucky. 

 Figs. 24-27. Ventral, dorsal, profile and anterior views of a characteristic individual ; showing the irregu- 

 lar dichotomous plication of the surface and the development of fold and sinus on brachial and 

 pedicle-valves respectively. 



Schoharie grit. Albany cuuivty. New York. 

 Fig. 28. An interior of the brachial valve ; showing the completed spondylium resting upon the bottom of 



the valve. 

 Fig. 2S. The interior of an incomplete pedicle-valve ; showing the form of the spondylium. 

 Corniferous limestone. Waterloo, New York. 



Pentamerella Pavilionensis, Hull. 



Fig. 30. Dorsal view of a large individual from which a portion of the brachial valve has been removed 



exixwing the inner surface of the sessile spondylium. 

 Fig. 31. The exterior of a pedicle- valve ; showing the well developed median sinus and the irregular 



plication. 



Hamilton shales. Canandaigua Lake, New York. 



Pentamerella dubia, Hull. 



Figs. 32, 83. Carilinal and profile views of the original specimen ; showing the form and proportions, and 

 the clearly defined cardinal area of the pedicle-valve. 

 Hamilton beds. Near Iowa City, loica 

 Pigs. 34, 35. Dorsal and ventral views of a characteristic specimen from which the shell is partially exfoIiate<l 



on the pe<licle-valve. 

 Fig«. 36, 37, 38. Profile, dorsal and ventral views of another exara])le having the cardinal Area obscuj-ely 

 defined and the surface covered with fine, regfular plications. 

 Hamdton beds. Littleton, Iowa. 



