444: MISSISSIPPIAN BRACHIOPODA 



Shumard. The originals of Shumard's species were from Washington and 

 Crawford Counties, Arkansas, and have evidently been lost, and his 

 illustrations are so imperfect that they can scarcely be recognized. The 

 only tangible character mentioned in the original description is the 

 number of plications, which are stated to be from 34 to 38 upon each 

 valve, a number which would correspond with examples of E. costata. 

 If these different forms are recognized as distinct, as is done here, 

 Shumard's name cannot be considered as having priority over E. 

 verneuiliana, and if used at all must be used as a substitute for E. costata. 

 Considering the uncertainty which must exist in the absence of the type 

 specimens, as to what E. marceyi really is, it seems best to drop that name 

 altogether and to use the names applied by Hall, which were clearly 

 defined and were illustrated by excellent figures. 

 Horizon. Salem limestone ; St. Louis limestone ; Chester group. 



EUMETRIA VERA (Hall) 



Plate LXXVI, Figs. 13-17 



1858. Retzia vera Hall, Geol. Iowa. vol. 1, pt. 2, p. 704, pi. 27, fig. 3a. 

 1894. Eumetria vera Hall and Clarke, Int. to Study of Brach., pt. 2, 

 pi. 37, figs. 8, 12. 



1894. Retzia vera Keyes, Mo. Geol. Surv., vol. 5, p. 95. 



1895. Eumetria vera Hall and Clarke, Pal. N. Y., vol. 8, pt. 2, pi. 51, 



figs. 36, 37. 



1909. Eumetria marcyi l Bassler, Va. Geol. Surv., Bull. No. II A., pi. 29, 

 figs. 4-5. 



Description. Shell of medium size, longer than wide, the greatest width 

 anterior to the mid-length of the shell, subovate in outline, the sides 

 diverging from the beak anteriorly in nearly straight or slightly convex 

 lines to the line of greatest breadth, anteriorly the outline is sub- 

 semicircular, often with a slight straightening of the anterior margin, 

 the hinge-line very short. The dimensions of three individuals are: 

 length of pedicle valve 25.5 mm., 20 mm. and 19 mm., length of brachial 

 valve 23.5 mm., 17 mm. and 17 mm., greatest width 26 mm., 19 mm. and 

 16 mm., thickness 16 mm., 11 mm. and 10 mm., length of hinge-line 6.5 

 mm., 5.5 mm. and 4.5 mm. 



Pedicle valve most convex posterior to the middle, the umbonal region 

 prominent and projecting posteriorly beyond the hinge-line, the surface 

 curving with a regularly diminishing curvature from the beak to the 

 anterior margin, the curvature gradually becoming more abrupt anter- 

 iorly along the lateral margins, and towards the cardinal extremities 

 becoming inflected, at the cardinal extremities the surface is again 

 slightly deflected to form a pair of minute auriculations which are some- 

 times nearly or quite obsolete; the beak is large, prominent and incurved, 

 and is pierced by a large circular foramen which encroaches notably 



