BRACHIOPODA. 85 



Surface striated by numerous fine strongly elevated striae, which are increased by 

 bifurcation and interstitial additions, and crenulated by fine closely arranged con- 

 centric striae. 



The interior of the ventral valve is marked by strong dental lamellae and a broad 

 flabellate muscular impression, which, in well-preserved specimens, shows the cordiform 

 imprint of the adductors, and a short low mesial septum in the upper part. 



The interior of the dorsal valve preserved deep dental sockets, with thick socket- 

 plates which support the duplicate cardinal process, each division of which is grooved 

 at the extremity. There is likewise a small process between the two branches of the 

 cardinal process; and below the hingeline, the flabelliform muscular impression is divided 

 by a low rounded mesial longitudinal ridge or obsolete septum. 



Remarks — The specimens identified with S. pandora are so rare, and imperfectly 

 preserved that a comparison is more nearly the correct word than identification. 



Occurrence — Rare in the-Mineola of Warren and Montgomery Counties. 



Family Productidae 



Genus Productella Hall 



Productella callawayensis (Swallow) 



Plate 11, i'gures 10 and 16; plate 15, figures 10, 11, 13 and 14 



1860. Productus Callawayensis (Swallow), Trans. St. Louis Acad. Sci., I, p. 640. 



1894. Productella marquessi Rowley, Am. Geologist, XIII, p. 153, figs. 7 and 8. 



1894. Produc'ella subalata Keyes. Geol. Survey Missouri, V, p. 52. 



1897. Productella marquessi Schuchert, Bull. U. S. Geol. Surv., 87, p. 316. 



1909. Productella marquessi Greger, Am. Jour. Sci., XXVII, p. 376. 



1909. Productella callawayensis Greger, Am. Jour. Sci., XXVII, p. 376. 



Swallow's description of P. callawayensis — "Shell small, thin, depressed, spinose, 

 varying from semiorbicular to suborbicular. Ventral valve very regularly convex, 

 but most so on the umbo, flattened towards the ears; break small, incurved to or slightly 

 over the cardinal line; umbo small, prominent, projecting a little back of the cardinal 

 line; ears large flattened triangular, slightly arched towards the cardinal line, rounded 

 on the outer angle; mesial sinus obsolete, or entirely wanting. Dorsal valve regularly 

 concave, most depressed in the middle in adult specimens, but nearer the beak in the 

 young; ears well defined, triangular, slightly arched; cardinal line as long or shorter 

 than the width of the shell; curved at the extremities towards the lateral margins and 

 down towards the center of the ventral valve. Surface marked with small, irregular, 

 iterrupted corrugations and striae; both valves thickly set with depressed spines, whose 

 bases are more or less prolonged into longitudinal plications; spines on the dorsal valve, 

 smaller. 



Length, .85; breadth, 1.12; thickness, .40." 



Rowley's description of P. marquessi — "This small shell is subcircular in outline. 

 Cardinal line of a little less length than the greatest width of the shell. Ventral valve 

 without striae but provided with a few slender spines, convex. Beak incurved. Cardinal 

 area very narrow, scarcely appearing more than a line. Dorsal valve deeply concave, 

 apparently without striae or spines. Lines of growth cross both valves. 



This little Productella resembles P. pyxidata Hall from the Lithographic limestone, 

 but is much smaller and from a lower horizon. Length of type 5/16, width 6/16 of an 

 inch." 



Description — Shell usually small but ranging to large, the small shells about equi- 

 dimensional but the large ones wider than long, the hingeline a little shorter than the 

 greatest width. Average specimens are about 7 mm. wide by 7 mm. long with a con- 

 vexity of the pedicle valve of about 3 mm. The largest specimen in the collection of 



