80 THE DEVONIAN OF MISSOURI. 



has a very convex valve flattened near the anterior and lateral margins as described by 

 Swallow for callawayensis. Swallow describes callawayensis as having "ears large, 

 well defined, and arched towards the cardinal border" and as having "numerous small, 

 rounded, granulated, radiating costae." The specimens having ears of this description 

 do not have fine plications but the plications run 8 to 14 to the centimeter with an 

 average of about 10. 



Occurrence — Snyder Creek shale, Callaway and Montgomery Counties. 



Stropheodonta inequiradiata Hall 

 Plate 11, figure 15; plate 14, figures 10 and 11. 



1857. Strophomena {Strophodonta) inaequiradiata Hall, Tenth Rep. N. Y. State Cab. 



Nat. Hist., pp. 113-114, figs. 1-3. 

 1861. Strophomena inaequistriata Billings, Canadian Jour. Sci., Arts, VI, p. 338, fig. 



113. 

 1863. Strophomena inaequistriata Billings, Geol. Canada, p. 367, fig. 375. 

 1867. Strophodonta inequiradiata Hall, Pal. New York, IV, p. 87, pi. 11, figs. 24-31 



pi. 12, fig. 12; pi. 13, figs. 6-11. 

 1874. Strophomena inaequiradiata Billings, Pal. Fossils, II, p. 24, fig. 13; pi. 2, figs. 



4 and 4a. 



1883. Strophodonta inaequiradiata Hall, Second Ann. Rep. New York State Geol., 

 pi. 45, figs. 13 and 14. 



1884. Strophodonta inaequiradiata Walcott, Mon. U. S. Geol. Survey, VIII, p. 120, pi. 

 11, fig. 11. 



1892. Stropheodonta inaequiradiata Hall and Clarke, Pal. New York VIII, pt. 1, 



pi. 14, figs. 13 and 14. 

 1897. Stropheodonta inaequiradiata Schuchert, Bull. U. S. Geol. Survey, 87, p. 422. 

 1909. Stropheodonta inaequiradiata Grabau and Shinier, North American Index 

 Fossils, I, p. 216, fig. 259. 

 Hall's description — "Shell semielliptical or semicircular, more or less gibbous, 

 approaching a hemispheric form; cardinal extremities sometimes salient, but often 

 rounded, and the cardinal line less than the width of the shell below. The ventral 

 valve varies from moderately convex to gibbous, often forming a somewhat regular 

 arch from beak to front, usually with the greatest convexity above the middle, depressed 

 and often concave between the umbo and the cardinal extremities, which (in perfect 

 shells) are somewhat salient; beak a little elevated above the hingeline, and incurved; 

 area very narrow, linear, and finely crenulate. The dorsal valve is concave, often in 

 a less degree than the convexity of the ventral valve; the disc sometimes very slightly 

 concave, and abruptly deflected or almost geniculate towards the front. 



The surface presents much variety of character and aspect, both in the original 

 shell and in its partial or entire exfoliation. The striae on the ventral valve are often 

 coarse and uneven, somewhat fasciculate, and often rising in ridges which in the ex- 

 foliated shell do not show the divisions. Some specimens have the striae sharp and 

 slender, and nearly equal, with wider plain intermediate spaces. On the dorsal valve the 

 striae are pretty uniform; the stronger ones being distant, sharp and elevated, with wide 

 intermediate spaces marked by extremely fine regular striae, from the midst of which, 

 as the shell increases, the elevated striae arise, dividing the space in which the smaller 

 striae are constantly increasing by intercalation." 



Remarks — The Mineola specimens are all internal casts of pedicle valves and are 

 not well preserved. Only one shows the fine striations between plications as shown in 

 figure 15 of plate 11. The most characteristic features of this shell are the increase 

 of plications near the middle of the pedicle valve by implantation, and the fine striae 

 that mark the spaces between the plications. Muscular impressions are preserved on 

 all of the specimens but they are of little aid in identification. 



Occurrence — Mineola of Montgomery County. 



