PLATE 48. 
Legend: d. Spondylium. VA. Cardinal area (pedicle-valve.) 
s. Median septum (pedicle- dp. Deltaria (remnants of deltidium ?). 
valve). 1. Cruralium., 
s. Median septum (brachial 
valve). 
BARRANDELLA, Hatt. 
Page 844. 
BaRRANDELLA LINGUIFERA, Sowerby. 
Figs. 1, 2. Dorsal and profile views of a normal individual; showing the 
character of the exterior and the well-defined median fold on the 
brachial valve. 
Fig. 3. A longitudinal median section of the valves; showing the small spon- 
dylium and extremely short median septum of the pedicle-valve, 
~ and one of the septal plates of the brachial valve. (DAVIDSON.) 
Wenlock limestone. Dudley, England. 
BaRRANDELLA VENTRICOSA, Hall. 
Figs. 4, 5, Dorsal and front views of a typical example; showing the fold upon 
the brachial valve, its faint plication, and the cavities of the median 
septa. 
Niagara dolomites. Waukesha, Wisconsin. 
PENTAMERELLA, Hatt, 
Page 845. 
PENTAMERELLA ARATA, Conrad. 
Figs. 6-8. Dorsal, profile and anterior views of a characteristic individual; 
showing the irregular dichotomous plication of the surface and the 
development of fold and sinus on brachial and pedicle-valves 
respectively. 
Schoharie group. Albany county, N. Y. 
Fig. 9. The interior of an incomplete pedicle-valve; showing the form of the 
spondylium. 
Fig. 10. An interior of the brachial valve; showing the completed spondylium 
(cruralium) resting upon the bottom of the valve. 
Corniferous limestone. Waterloo, N. Y. 
PENTAMERELLA DustA, Hall. 
Figs. 11-13. Dorsal, ventral and profile views of an example having the car- 
dinal area obscurely defined and the surface covered with fine, 
regular plications. 
Figs. 14, 15. Dorsal and profile views of a characteristic specimen from which 
the shell is partially exfoliated on the pedicle-valve, 
Hamilton beds. Littleton, Iowa. 
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