The !N'ew Species of Brachiopoda.. 341 



elongate and very deeply impressed, the umbonal portion of this 

 valve being considerably thickened. 



Surface covered with numerous very fine radiating striae. 



Length of the type specimen, 19 mm.; width, 18 mm.; depth, 

 9 mm. 



Hudson Kiver group. East Tennessee, 



Orthis (Dalmanella) superstes. 



Plate 4, figs. 15-18. 



Orthis {Dalmanella) superstes, Hall. Palaeontology of N. Y., vol. VIII, pt. 1, 

 p. 342, pi. V c, figs. 44-47. 1892. 



Shell of small size and having the general form and expression 

 of 0. hyhrida, Sower by. Hinge-line short, beaks but slightly 

 elevated. Marginal outline varying from subquadrate to sub- 

 circular. Yalves about equally convex. In the pedicle- valve the 

 beak is somewhat inflated and slopes evenly in all directions for 

 nearly one-half of the shell; from this point onward is a broad, 

 low median sinus, which is most conspicuously developed in old 

 and gibbous shells. In rare instances there is a low elevation in 

 the bottom of this sinus. The opposite valve also bears a median 

 sinus which takes its origin at the beak. In the interior of the 

 pedicle- valve the muscular area is sharply defined, subquadrate 

 in outline, the adductor scars small and the diductors well 

 developed. In the brachial valve the cardinal process and crural 

 plates are prominent; the muscular area well defined and 

 quadruplicate. 



The external surface of the valves is covered with fine, elevated 

 striae, of which twenty of the coarsest reach the beak; this number 

 increasing by intercalation to about fifty at the margin. J^ear 

 the margin very fine concentric striae are visible. 



Length of normal individual, 12 mm. ; width, 13 mm. ; depth, 

 9 mm. 



Chemung group. J}^ear Howard, Steuben county, iT. Y. 



Orthis (Rhipidomella) Oweni. 

 Plate 4, figs. 24-26. 



Orthis {Rhipidomella) Oweni, Hall. Palaeontology of N. Y., vol. VIII, pt, 1, 

 p. 342, pi. vi, figs. 19-21. 1892. 



Shell having somewhat the outline of 0. Vanuxemi, but more 

 elongate transversely and gently sinuate or emarginate on the 



