CoNcHIDIUM EXPONENS, Hall. 
Figs. 11, 12. The interior of a brachial and pedicle-valves of a strongly costate 
shell ; showing the septa and spondylium. 
Niagara group (Halysites bed). Lowisville, Kentucky. 
ConcHipiuM LAQuEATUM, Conrad (=PsNTAMERUS NuBILIS, Emmons). 
Fig. 18. Profile view of an internal cast of a rather narrow shell; showing 
the contour, character of the plication and smooth umbonal slopes. 
Fig. 14. Longitudinal section of conjoined valves; showing the extent of the 
median septum of the pedicle-valve quite to the anterior margin of 
the valve, its concave anterior edge, the projecting extremity of the 
spondylium and, in the brachial valve, the relatively short spondy- 
lium and septa, and the projection of the crural apephyres: 
Niagara dolomites. Delphi, Indiana. 
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