BRACHIOPODA. 243 



Pedicle valve commonly strongly convex transversely, the greatest convexity in 

 the region of the greatest width. Shell surface sloping uniformly from the middle to- 

 wards the lateral margins to near the edge where it becomes abruptly inflected, and 

 bends almost at right angles toward the other valve. Beak fairly high, closely in- 

 curved over the umbo of the opposite valve. 



Brachial valve less convex than the pedicle, the surface sloping more gently to the 

 lateral margins, but near the edge being deflected in a similar manner. Beak less ele- 

 vated than the beak of the pedicle valve. 



Surface of both valves marked by fine, radiating costae, 3 occupying the space of 

 1 mm. These are crossed by conspicuous concentric growth lines, which show clearly 

 the outline of the shell at various ages. 



Remarks — This species which occurs abundantly in the Little Saline limestone, is 

 represented by both entire specimens and by the separate valves. Due to the condi- 

 tion of preservation the punctate shell structure so characteristic of this genus has not 

 been observed in any of the specimens studied. The species is distinguished by the 

 distinct spatula-shaped shell, the high convexity of both valves particularly the pedicle, 

 and the flattened character of the lateral margins in mature individuals. 



Horizon — Lower and upper beds. 



Figured specimens No. 27506, Walker Museum. 



Rensselaeria cf. stewarti Clarke 

 Plate 64, figures 13-15 



1907. Rensselaeria stewarti Clarke, Mem. N. Y. State Mus. No. 107, p. 239. 



1908. Rensselaeria stewarti Clarke, Mem. N. Y. State Mus. No. 9, pt. 2, p. 38, pi. 7, 

 figs. 10-20. 



Description — Shell of medium size, usually broader than long, semi-circular in out- 

 line. An average individual measures 29 mm. in length and 31 mm. in width. Hinge 

 line equal to the greatest width. Cardinal margins sloping abruptly from the beaks, 

 and terminating in rounded extremities. 



Pedicle valve convex, the maximum convexity in the umbonal region, from which 

 the surface slopes uniformly, gradually flattening out toward the anterior and lateral 

 margins. Qeak high, triangular, incurved over the hinge line. 



Surface marked with simple radiating plications, these gradually diminish in size 

 toward the posterior margin until well above the middle of the shell they become obscure 

 and apparently disappear. In some specimens the plications persist throughout the 

 whole length of the shell. In general one plication occupies the space of 1 mm., at the 

 anterior margin. Posterior to the middle, there are two and sometimes even three in 

 1 mm. The plications are crossed by coarser, concentric growth lines. 



Remarks — This species is represented by the exteriors of the pedicle valve. It 

 resembles Rensselaeria stewarti Clarke, from the Dalhousie beds of New Brunswick, 

 Canada, but has a less convex pedicle valve, and a less prominent umbonal region. 

 The species also resembles Rensselaeria atlantica Clarke, which occurs in the Chapman 

 sandstone immediately above the Dalhousie beds and it may prove to be more closely 

 allied to this form than to the former. Since many of the Little Saline species are 

 identified with forms in the Grand Greve limestone which is a higher horizon than the 

 Chapman, it would seem plausible that the present form may agree more closely with 

 the form in the higher horizon. 



Horizon — Lower and upper beds. 



Figured specimens Nc. 27505, Walker Museum, 



