CAMAROPHORIA 



501 



median ridge along the concave side of the cruralium (figures 2m, n, o), 

 the cruralium itself gradually increases in elevation and in width, finally 

 becoming narrower and terminating abruptly. In the pedicle valve the 



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Figure 2. — Cross-sections of the rostral Portion of the Pedicle Valve, and a Like Series 

 of the Brachial Valve, of Camarophoria hamhurrjensis n. sp. 



This series of ten cross-sections ( X - % ) ^^ from specimens from tlie Kinderliook oolite 

 at Hamburg, Callioun County, Illinois 



dental lamellae are not joined to form a true spondylium, supported by a 

 median septum from the floor of the valve, but they do form a spon- 

 dylium-like process which rests directly upon the floor of the valve. 



CAMAROPHORIA EXPLANATA (McCHESNEY) 



A second species which is apparently a typical member of the genus 

 Camaroplioria is C. explanata (McChesney), which was referred to the 

 genus Pugnax by Hall and Clarke. Externally this species closely re- 

 sembles certain rhynchonelliform shells which have commonly been!' 

 referred to Pugnax. The example illustrated by Hall and Clarke was a 

 very perfect sulphur cast of McChesney's type specimen, which of course 

 gave no indication of median septa in either valve and was naturally 

 referred to Pugnax, but these characters were observed by Schuchert, who 

 correctly referred it to CamaroplwriciJ In figure 3 a carefully prepared 

 series of sections of this species is shown. The lateral processes from the 

 sides of the median septum of the brachial valve are short and are situated 

 high above the floor of the valve (flgures 3c, d, e). In the section nearest 

 the apex of the brachial valve these cruralium processes are apparently 

 consolidated with the beginning of the hinge-plate (figure 3&), but the 

 separation is complete from its origin, the distal margins of the processes 

 not being joined to the under side of the hinge-plate for a short distance, 

 as in C. schlotheimi. The median septum rising from the concave floor 



♦ Bull, of the U. S. Geological Survey, No. 87, p. 162. 



