142 THE DEVONIAN OF MISSOURI. 



insecure basis for identification. Many pedicle valves show the truncation. Prosser 

 and Kindle state that the species is recognized by "its small size, gibbous and truncate 

 ventral valve., flattened cardinal extremities, slightly concave dorsal valve which is 

 wrinkled and pustulose on the interior, and the scattered surface spines on both Valves." 



Superfamily Pentameracea 



Family Pentameridae 



Genus Pentamerella Hall 



Pentamerella arata (Conrad) 



Synonomy and description on pages 87 and 88 



Figure 16 on plate 16, and figures 17-23 on plate 17 . 



Remarks — Only two specimens from the Grand Tower limestone are known to the 

 writer. These specimens are rather massive and broad for the species. None of the 

 Mineola specimens is as large as the ones from the Grand Tower. 



Order Telotremata 



Superfamily Rhynchonellacea 



Family Rhynchonellidae 



Genus Camarotoechia Hall and Clarke 



Camarotoechia congregata (Conrad) 



Plate 34, figures 7, 8, 9, 10, 11 and 12 



1841. Atrypa congregata Conrad, Fifth Ann. Rep. New York Geol. Survey, p. 55. 

 1867. Rhynchonella (Stenocisma) congregata Hall, Pal. New York, IV, pp. 341-342, pi. 



54, figs. 44-59. 

 1897. Camarotoechia congregata Schuchert, Bull. U. S. Geol. Surv., 87, p. 165. 

 1901. Camarotoechia congregata Kindle, Indiana Dept. Geol. Nat. Res., 25th Ann. Rep., 



p. 585. 

 1913. Camarotoechia congregata Prosser and Kindle, Maryland Geol. Surv., Middle 

 and Upper Devonian, pp. 171-173, pi. 14, figs. 15-17. 



Hall's description — "Shell robust, varying from short-ovate to subglobose; length 

 and width nearly equal or a little wider than long; front rounded or straight in the 

 middle; apex pointed. 



Ventral valve convex at the sides, depressed in the middle; mesial sinus often be- 

 ginning at about one-third the length from the apex, and becoming conspicuous towards 

 the front; beak, in old shells, closely arcuate over the apex of the opposite valve; in 

 young shells, nearly straight or slightly incurved. 



Dorsal valve gibbous in old shells, regularly convex in young specimens; mesial 

 fold scarcely conspicuous on the upper half of the shell, sometimes prominent near 

 the margin; sides curving abruptly to the junction with the opposite valve. 



Surface (in young shells) marked by only nine or ten distinct subangular or rounded 

 plications; in older shells, by eighteen to twenty-two, of which three or four occupy 

 the mesial sinus and four or five the mesial fold. In the two larger specimens observed, 

 there are but three plications in the sinus, and this is the prevailing number. Slender 

 concentric striae, sometimes a little imbricated in front, mark the surface of the shell."' 



Remarks — The species is abundant in the St. Laurent limestone. Many speci- 

 mens are moulds of the interior. Average specimens are indistinguishable from average 



