cl-\rk: new bl,\stoids and brachiopods. 375 



shaped crural cavity; the hinge-plate is divided, the inner margin 

 of each lateral portion being supported by one of the lateral walls of 

 the crural cavity. No cardinal process is present. 



It will be seen that Axiodeaneia has the external characteristics of 

 Rhynchotetra with the internal arrangements of Paryphorhynchus. 



Axiodeaneia platypleura, sp. nov. 

 Plate 2, fig. 25-32. 



Description. — Shell narrowly subtriangular, nearly twice as long as 

 wide, greatest width one third the length from the anterior end. The 

 sides are flat, two thirds the length of the shell, perpendicular to the 

 plane of the valves, converging toward the beaks, giving the shell a 

 distinctly wedge-shaped appearance. There is no hinge-area. The 

 beak of the pedicle-valve projects beyond the brachial valve slightly. 

 The valves are subequally convex from beak to anterior end; the 

 brachial valve is well rounded from side to side, the pedicle-valve being 

 nearly flat. Both valves are strongly plicated, with the anterior 

 border deeply dentate. There are usually eight plications on the 



s Q Q 



Fig. 4. Six serial sections of the rostral portion of a specimen of Axiodeaneia platy- 

 pleura Clark. X 3- 



pedicle-valve and nine on the brachial; on both valves the lateral 

 plications become ob.solete towards the beaks. The pedicle-valve is 

 marked by a strong median furrow, corresponding to which in the 

 brachial valve is the strong median plication. The plications are sub- 

 angular at the anterior end; the furrows are wide and rounded. In 

 well-preserved specimens the whole surface is covered with fine radi- 

 ating striae. Concentric markings are present, but indistinct. 



Internally the pedicle-valve possesses two strong dental lamellae 

 which become' free from the valve at their lower end slightly in front 

 of the articulated portion of the valves; then rapidly diminish in 

 length and become obsolete at about one third the length of the 



