138 THE DEVONIAN OF MISSOURI. 



The well-marked specimens are usually small or of medium size." 

 Remarks — Four specimens from the Grand Tower limestone are referred to this 

 variety; mainly on the basis of the distant striae with the finer striae between. One 

 brachial valve is strongly convex with the greatest convexity near the middle. 



Occurrence — Grand Tower limestone, Little Saline Creek, Ste. Genevieve County. 



Schuchertella pandora Hall 



Remarks — None of the specimens from southeastern Missouri has the area of the 

 pedicle valve well preserved. Several specimens are in the Walker Museum collections, 

 but this seems to be a rather rare form. 



Occurrence — Grand Tower limestone, Little Saline Creek, Ste. Genevieve County. 



Family Productidae 



Genus Chonetes Fischer 



Chonetes coronatus (Conrad) 



Plate 32, figures 1, 2 and 3 



1842. Strophomena carinata Conrad, Jour. Acad. Nat. Sci., Philadelphia, VIII, p. 257, 



pi. 14, fig. 13. 

 1854. Chonetes littoni Norwood and Pratten, Jour. Acad. Nat. Sci., Philadelphia, III, 



pi. 25, pi. 2, fig. 4. 

 1857. Chonetes coronata Hall, Tenth Rep. New York State Cab. Nat. Hist., p. 146, 



figs. 1, 2. 

 1867. Chonetes coronata Hall, Pal. New York, IV, pp. 133-137, pi. 21, figs. 9-12. 

 1897. Chonetes coronatus Schuchert, Bull. U. S. Geol. Surv., 87, p. 173. 

 1901. Chonetes coronatus Kindle, Indiana Dept. Geol. Nat. Res., 25th Ann. Rep., pp. 



602-603, pi. 4, fig. 7. 

 1903. Chonetes coronatus Weller, New Jersey Geol. Surv., vol. 3, p. 380, pi. 53, fig. 6. 

 1909. Chonetes coronatus Grabau and Shimer,, North American Index Fossils, I, p. 



236, fig. 288. 

 1913. Chonetes coronatus Prosser and Kindle, Maryland Geol. Surv., Middle and 



Upper Devonian pp. 148-150, pi. 11, figs. 18-21. 

 Hall's description — "Shell transverse, somewhat broadly elliptical, the hinge 

 line being sometimes shorter than the width of the shell and the cardinal angles rounded ; 

 in others it is often equal to the greatest width of the shell, and its form is semioval 

 with the lateral margins nearly rectangular to the hingeline, the width being about once 

 and a half as great as the length. The cardinal angles are sometimes produced in short 

 acute auriculate extensions. 



Ventral valve varying from moderately convex in the younger shells, to very gibbous 

 in the older ones; often a little flattened below the umbo, and this plane space gradually 

 widening to the front. Sometimes there is a shallow undefined depression along the 

 middle of the valve. The outline of the valve presents a very regular convexity, while 

 it is abruptly depressed towards the cardinal extremities, which are flattened and a 

 little deflected to the ventral side. 



The dorsal valve is variably concave, sometimes following nearly the contour of 

 the ventral valve, but often very moderately concave or nearly flat in the middle and 

 upper part, and more suddenly deflected towards the front and lateral margins, flattened 

 at the cardinal extremities, and a little concave just below the hinge line. 



