﻿105 Paleontology 27 



Leiorhynchus utahensis n. sp. 

 PL III figs. i-ic. 



Shell large, subglobose, the valves unequally convex. 



The pedicle valve is characterized by a broad si'nus which is 

 obsolete near the umbone but deepens and widens rapidly toward 

 the front, occupying half the width of the shell in the latter 

 region. In the anterior third of the shell the sinus bends ab- 

 ruptly, forming a tonguelike extension into the end of the fold of 

 the opposite valve. 



A nearly flat area lies on either side the sinus in the posterior 

 part of the valve which is abruptly geniculated near the margin 

 of the shell, forming a broad band flanking the margin of the 

 shell from the beak to the tonguelike extension of the sinus. 

 Three to five coarse, rounded plications occupy the sinus. Sur- 

 face smooth on either side. Beak small and rather closely 

 incurved. 



Dorsal valve convex, with a broad fold at the front becoming 

 obsolete near the beak. Three or more plications occupy the 

 fold (three in the only specimen observed which belongs to a 

 young shell) . Shell smooth on either side of the fold and curving 

 uniformly to the margin. 



The largest specimen in the collection has a length and breadth 

 of 30 mm. This species is closely related to an undescribed form 

 occurring in the Threeforks shale at Logan and Melrose, Montana, 

 but differs from that species in the more triangular outline of the 

 posterior part of the shell and in being narrower. The post- 

 cardinal slopes of the Montana shells also seem to be more 

 strongly inclined. The differences between the two forms, how- 

 ever, are probably not much more than varietal. 



Locality. — Paradise, P. O., Utah. 



Hypothyris (?) globular is n. sp. 

 PL I. figs. 9~9b. 

 Shell small and globulose, the globular form interrupted only 

 by the slightly projecting beak of the pedicle valve. Valves of 

 equal size. 



