276 SYNOPTIC COLLECTION. 



the "shoe-lifter" or spondylium, which serves the same 

 purpose. 



BRACHIOPODA. TELOTREMATA. 



One of the most primitive members of the Telotremata 

 is Protorhyncha aequiradiata Hall (PI. 675, figs. 1-3). 

 We know nothing of the early development of this spe- 

 cies, but the adult is primitive in its characteristics, so 

 that it is reasonable to assume that the young stages 

 must have been still more primitive. It has been ascer- 

 tained in living genera of this order (Telotremata) that 

 in the nepionic and early neanic stages the pedicle passes 

 out freely between the two valves, the opening being 

 shared by both as in the Atremata. In the later neanic 

 period the shell layers extend entirely round the pedicle, 

 so that this organ becomes restricted to the pedicle valve. 

 In the adult or ephebic stage of Protorhyncha (figs. 1-3) 

 the pedicle opening is triangular, and is rarely closed by 

 plates of any kind. 



There is no cardinal area in Protorhyncha, according 

 to Schuchert, 1 while Hall and Clarke 2 figure a small rudi- 

 mentary area (fig. 2). The adult shell is narrow at the 

 beak or rostrate in form (PL 675, fig. i, internal cast of 

 the brachial valve ; fig. 3, internal cast of the pedicle 

 valve). 



The arms of Protorhyncha are fleshy and not strength- 

 ened by limy supports; even crura, the parts to which the 

 brachial supports are fastened, are not developed. 



According to Schuchert 3 the oldest Rhynchonelloids 

 are rostrate in form, like Protorhyncha, and the ontogeny 

 of several living species of the genus has not revealed a 

 long-hinged stage. 



1 Bull. U. S. Geol. Surv., no. 87, 1897, p. 87. 



2 i3th Ann. Rep. State Geol. N. Y., 1893. 



3 Loc. cit., p. 83. 



