PLATE LXXI—Continued. 
Genus PENTAMERELLA, Hall. 
Page 241. 
Pentamerella arata, Coiiiad. 
Figs. 21, 22. Longitudinal profiles of pedicle-valves; showing the spondylium 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 gvit. Albany county, New York. ^ 
Fig. 28. An interior of the brachial valve ; showing the completed spondylium resting upon the bottom of 
the valve. 
Fig. 29. The interior of an incomplete pedicle-valve ; showing the form of the spondylium. 
Corniferous limestone. Waterloo, Neio York. 
Pentamerella Pavilionensis, Hiill. 
Fig. 30. Dorsal view of a large individual from which a portion of the brachial valve has been i-emoved 
exjiosing the inner surface of the sessile spondylium. 
Fig. 31. The exterio]’ of a pedicle-valve ; showing the well develo^jed median sinus and the irregular 
plication. 
Hamilton shales. Canandaigua Lake, New York. 
Pentamerella dubia, Hfill. 
Figs. 32, 33. Cardinal and profile views of the original specimen; showing the form and proportions, and 
the clearly defined cardinal area of the ijedicle-valve. 
Hamilton beds. Near Iowa City, Iowa. 
Figs. 34, 35. Dorsal and ventral views of a characteristic specimen from which the shell is partially exfoliated 
on the pedicle-valve. 
Figs. 36, 37, 38. Profile, dorsal and ventral views of another example having the cardinal area obscurely 
defined and the surface covered with fine, regular plications. 
Hamilton beds. Littleton, Iowa. 
