The E'ew Species of Brachiopoda. 369 



the umbo of the opposite valve. The pedicle valve has an acute, • 

 suberect beak, which is not arched posteriorly but rises directly 

 from the cardinal margins. Below it is a broad delthyrium 

 without evidence of deltidial plates. There is no hinge-line but 

 the margins of the delthyrium make subacute angles with the 

 lateral margins of the valve. Cardinal slopes very broad and 

 abrupt. The pedicle-valve is flattened above, while that of the 

 brachial valve is evenly and deeply convex; it also shows a 

 tendency to trilobation or obscure radial plication. Surface of 

 both valves otherwise smooth. Internal apparatus as in Pen- 

 tamerus ohlongus. 



Niagara dolomites. Wear Ifilwaukee^ Wisconsin, 



Barrandella Areyi. 



Plate 13, figs. 1-3. 



Barrandella Areyi, Hall. Palaeoiitology of N. Y., vol. VIII, pt. 2, p. 368, pi. 

 ixxi, figs. 14-16. 1894. 



Shell small, ventricose, with sinus on the pedicle-valve and fold 

 on the brachial valve. Surface on both valves rather sharply and 

 coarsely plicated, the largest plication being in the median sinus, 

 with traces of finer ones on the slopes of the sinus. The median 

 fold bears two well-defined plications with faint traces of others, 

 while on each lateral slope of the valves there are four or five less 

 sharply angular ribs. 



Clinton group. Rochester^ N. Y. 



Gypidula Romingeri. 



Plate 12, figs. 7-13. 



Gypidula Romingeri, Hall. Palaeontology of N. Y., vol. VIII, pt. 2, expl. pi. 

 Ixxii, figs. 27-33. 1894. 



Shells piano , or subplano-convex ; marginal outline circular 

 or subelliptical. Pedicle- valve highly convex, regularly arched 

 from beak to margin. Hinge-line short, straight; cardinal area 

 distinct, narrow, sometimes with remnants of deltaria or deltid- 

 ium. On the interior the pedicle- valve bears a short, free spondy- 

 lium and the brachial valve a sessile cruralium which may extend 

 for one-half the shell's length. The surface of both valves is 

 covered with coarse, often irregular and bifurcating plications. 



Hamilton group. Aljyena, Michigan. 

 47 



