448 • STUART WELLER 



Remarks. — The relationships of this genus cannot be certainly 

 determined from the material available for study. The general 

 contour of the shell at once suggests its affinity with the tere- 

 bratuloid, loop-bearing shells, as also does the character of the 

 foramen of the pedicle valve, and so far as it can be observed the 

 delthyrium and its covering. The shell structure has not been 

 certainly determined. Upon one example a punctate structure 

 is slightly suggested, but that characteristic structure of the tere- 

 bratuloids cannot be said to be demonstrated. The characteristic 

 of these shells which is most foreign to the terebratuloids is the 

 strongly developed mesial septum of the pedicle valve, which 

 evidently supports a well-developed spondylium, and the presence 

 of this character in association with a strong median septum in 

 the brachial valve suggests the family Pentameridae, but it has 

 not been determined that a cruralium accompanies this median 

 septum of the brachial valve. This feature of a median septum 

 in the pedicle valve has not been recognized heretofore among the 

 loop-bearing terebratuloids, although there is perhaps no reason 

 why it should not exist, but a median septum in the brachial valve 

 occurs in at least one genus of these shells. 



In any event the characters exhibited by these shells exclude 

 them from any described genus among either the terebratuloids 

 or the pentameroids. The presence of a pedicle median septum 

 is sufficient to differentiate the genus from any other of terebratu- 

 loids, if indeed it be one of these shells, and the characters of the 

 foramen and delthyrium differentiate it from any pentameroid. 

 The shell perhaps agrees most closely in the sum of all the char- 

 acters present with the spire-bearing Camarophorella, but there 

 is no evidence, in the specimens observed, of the presence of a 

 brachial platform associated with the median septum of that 

 valve, as is true in Camarophorella. 



Genotype. — R. fabulites (Rowley), Burlington white chert, 

 Louisiana, Mo. 



