204 MISSISSIPPIAN BRACHIOPODA 



Brachial valve more convex than the pedicle, becoming gibbous in 

 front in full grown shells, the surface sloping from a point at or near 

 the anterior margin with a more or less gentle convexity to the beak, 

 the lateral slopes oi' the valve rather strongly convex from the beak 

 to the front; mesial fold strongly elevated in front; beak incurved be- 

 neath that of the opposite valve; the plications similar to those of the 

 opposite valve, two or three occupying the mesial fold, with about two 

 or three upon each lateral slope. 



The surface of the shell marked by minute concentric lines of growth, 

 and in adult shells by a few, more or less irregular, stronger ones towards 

 the front margin. 



Remarks. This species was referred to the genus Camaroplwria by 

 Whitfield, and all later writers have followed him in this reference. 

 Authentic specimens, however* from Hull's Hollow, above Alton, which 

 is, or is very near, the typical locality for the species, show that the 

 dental lamellae of the pedicle valve continue separately to the bottom 

 of the valve and are not united to form a spondylium supported by a 

 median septum as is true in Camarophoria. Furthermore, the rostral 

 cavity of the brachial valve is entirely lacking in lamellae of any sort, 

 there being no median septum, and no crural cavity, the internal charac- 

 ters of both valves being exactly as in typical representatives of the 

 genus Pugnax. 



Horizon. Salem limestone. 



PUGNAX QUADRIROSTRIS Beede 

 Plate XXV, Figs. 34-36 



1906. Pugnax ? quadrirostris Beede, 30th Ann. Rep. Geol. Surv. Ind., 

 p. 1306, pi. 19, figs. 4-4c. 



Description. Shell very small, subquadrangular in outline, the length 

 and breadth subequal, the greatest width near the middle of the shell. 

 The dimensions of a nearly perfect specimen are : length 3 mm., width 3.4 

 mm., thickness 2 mm. 



Pedicle valve convex in the umbonal region, the surface curving ab- 

 ruptly from the umbonal region to the postero-lateral margins, trans- 

 versely between the points of greatest lateral extension the surface is 

 nearly flat, anteriorly the valve curves strongly towards the opposite 

 valve and is produced into a broad, elongate, lingual extension whose 

 length in the specimen observed is more than one-half the total length of 

 the valve ; mesial sinus originating near the beak as a narrow, rather ob- 

 scure, slightly impressed furrow, anteriorly it merges into the broad, 

 shallow mesial depression which extends nearly to the lateral extremities 

 of the valve and includes the entire lingual extension ; beak short, a little 

 incurved ; the delthyrium nearly closed by the beak of the opposite valve ; 



