PLATE LXXI— Continued. 



Genus PKNTAMEKELLA, Hall. 



Page 241. 



Pentamerella arata, CoihikI. 



Figs. 21, 22. Longitudinal profiles of pedicle-valves; showing the spomlylium and the variation in the 



development of the siippoi-ting septum. 

 Fig. 28. 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 sijondylium. 

 Corniferous limestone. Near Junt-tion City, Kentucky. 

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

 lar dichotomou.s plication of the surface and the development of fold and sinus on brachial and 

 pedicle-valves respectively. 



Schoharie gi'it. Albany county, New Yorlc. 

 Fig. 28. An interior of the brachial valve ; showing the completed spomlj Hum re.sting upon the liottora of 



the valve. 

 Fig. 29. The interior of an incomplete pedicle-valve ; showing the form of the spondylium. 

 Corniferous limestone. Waterloo, New York. 



Pentamerella Pavilionen.si.s, Hall. 



Fig. 31). Dor.sal view of a large individual from which a portion of the brachial valve has been removed 



exposing the inner surface of the sessile .spondylium. 

 Fig. 31. The exterioi' of a pedicle-valve ; shovring the well developed median sinus and the irregular 



plication. 



Hamilton shales. Canajidaigiux Lake, New York. 



Pentamerella dubia, Hall. 



Figs. 32, 33. Cardinal and profile views of the oi-iginal specimen; showing the form and proimrtions, and 

 the clearly defined cardinal area of the pedicle-valve. 

 Hamilton beds. Near Iowa City, Iowa 

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



on the pedicle-valve. 

 Figs. 36, 37, 38. Profile, doi-sal and ventral views of another example having the cardinal area obscurely 

 defined and the surface covered with tine, regular plications. 

 Hamdton Ijeds. Littleton, Iowa. 



