CAMAROPHOMA 499 



Camarophoria. Hall and Clarke have referred all those rhynchoneli- 

 form shells possessing a median septum in each valve, a ventral spon- 

 dylium, and a dorsal crnralium to Camarophoria, and their diagnosis of 

 that genus is clearly made, at least in part, from such rhynchonelliform 

 shells as B. subcuneata and B. subtrigona, which are illustrated hy them 

 as typical of the genus. For the present study the essential characters of 

 the genus Camarophm'ia have been determined by grinding specimens of 

 C. schlotheimi from the Permian of Germany. Drawings of a series of 

 eleven cross-sections of this shell are here persented in figure 1. The 

 most diagnostic characters of the genus are found in the brachial ^'alve 

 where the hinge-plate is undivided and is supported by a strong median 

 septum. From the lateral faces of the median septum a pair of hori- 

 zontal processes arise close to the posterior extremity of the shell (figures 

 Ic, d, e), which at first slope broadly and then curve more narrowly 



Figure 1. — Cross-sections of the rostral Portion of Camarophoria schlotheimi {von 



Buch) 



This series of eleven cross-sections (X 2%) is from a specimen from tlie Permian of 



Possnecli, Germany 



toward the hinge-plate with which the distal portions of the processes 

 are joined posteriorly. Before the articulation of the valves is passed, 

 however, the distal margins of the processes become free from the hinge- 

 plate (figure le), and they constitute the two sides of a concave crura- 

 lium supported by a median septum from the floor of the valve, and in 

 turn bearing a continuation of this septum along the middle line of its 

 concave side which supports the undivided hinge-plate. The hinge-plate 

 terminates abruptly in front, and is doubtless continued anteriorly in the 

 crura, although these processes were not preserved in any of the examples 

 sectioned. The cruralium continues anteriorly beyond the termination 

 of the hinge-plate, and for a short distance the continuation of the me- 

 dian septum upon the concave side of the cruralium persists (figure 1/), 

 although it becomes rapidly reduced and soon disappears. The cruralium 

 continues with increasing elevation from the floor of the valve and in- 



