BRACHIOPODA. 135 



and still finer striae between the latter. In other specimens there are wider spaces of 

 finer equal striae between the stronger ones; and in still other examples, the striae are 

 nearly all strong and sharply elevated, with few finer ones, which soon rise to the strength 

 of the others. Close undulating concentric striae cover the whole surface. The dorsal 

 valve is marked by distant sharp elevated striae, between which there are from three to 

 six and rarely ten finer striae, which are very finely crenulated by concentric striae." 



Remarks — This species is rare. Only very imperfect specimens are in the Walker 

 Museum and none in the University of Missouri collections. 



Occurrence — Grand Tower limestone of Little Saline Creek. 



Stropheodonta demissa (Conrad) 



Described on p. 77. Figured on plates 5, 11, 14 and 61 



Specimens from the Grand Tower are small, comparable in size to those from the 

 Mineola. Some specimens from the Beauvais sandstone are of average size but for the 

 most part they are small. Specimens from the St. Laurent are small and rare. 



Stropheodonta patersoni Hall 

 Plate 32, figures 10 and 11 



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



Hist., p. 114, figs. 1-5. 

 1867. Strophodonta patersoni Hall, Pal. New York, IV, pp. 89-90, pi. 12, figs. 9-12; 



pi. 13, figs. 1-5. 

 1897. Stropheodonta patersoni Schuchert, Bull. U. S. Geol. Surv. 87, p. 425. 

 1909. Stropheodonta patersoni Grabau and Shimer, North American Index Fossils, I 



pp. 215-216, fig. 258. 

 1912. Stropheodonta patersoni Kindle, Bull. U. S. Geol. Surv. 508, p. 75, pi. 3, figs. 



5, 6. 

 Hall's description — "Shell semioval. Ventral valve convex, becoming gibbous in 

 the middle, somewhat deeply deflected at the sides and front; sometimes marked by 

 a few radiating undulations or folds, which affect both ventral and dorsal valves to- 

 wards the front; hinge line straight; extremities often salient. 



Surface marked by distant elevated radiating striae, and the intermediate spaces 

 by undulating fine striae, and crossed by short abruptly arching wrinkles which are 

 interrupted by the strong radiating striae. The finer radiating striae on the ventral 

 valve are from three to ten or twelve between the stronger ones; while on the dorsal 

 valve the spaces are wider, and there are from ten to twenty finer striae between the 

 stronger ones. The finer striae are crossed by equally fine concentric striae, giving the 

 entire surface a delicately cancellated appearance." 



Remarks — This is a rare form which is represented in the University of Missouri 

 and Walker Museum collections by fragments only. The peculiar markings near the 

 hingeline give the main basis for identification. 



Occurrence — Grant Tower limestone, Little Saline Creek. 



Genus Leptostrophia Hall and Clarke 



Leptostrophia perplana (Conrad) 

 Plate 35, figures 15 and 16 



1842. Strophomena perplana Conrad, Jour, Acad. Nat. Sci., Philadelphia, p. 257, pi. 



14, fig. 11. 

 1867. Strophodonta perplana Hall.Pal. New York, IV, pp. 92, 98-101, pi. 11, fig. 22; 



pi. 12, figs. 13-15; pi. 17, fig. 1. 



