BRAcHTOPODA. 851 
shell, where it meets a similar marginal inflexion from the oppo- 
site valve. These produce the sharp introversion of the lateral 
margins which is also one of the characteristics of the genus 
MeGALANTERIS. 
The surface of the valves is covered with fine, hair-like radiat- 
ing striz, which are often visible only near the margins or at 
their thickened extremities on the inflexed portions of the 
shell. 
On the interior the dental lamellz are short and do not rest 
upon the valve. The hinge-plate is supported by two vertical 
septa, the median cleft and visceral foramen are more or less 
obscured and with sometimes a bilobed callus in its place. The 
brachidium has long, straight jugal processes and the triangular 
anterior plate in numerous specimens shows that the posterior 
rod-like process from the median ridge of that plate extends 
upward almost to the crura, but terminates abruptly and has no 
connection whatever with the latter. 
(Type, Beachia Suessana, Hall. Oriskany sandstone). 
Newberria, Hall. 1891. 
(Plate 51, figs. 12-19.) 
Shell elongate-ovoid, having the general contour and external 
aspect of Rensspi=ria and Ampuicenta, but without the strongly 
radiate-striate surface prevailing in the former genus and less 
strongly developed in the latter. The greatest convexity of the 
valves is in the umbonal region, or above the middle of their 
length, and in some forms the surface is distinctly flattened over 
the lateral slopes, leaving the median portion of the valves very 
prominent and sometimes subangular. The cardinal and lateral 
margins are regular, even and not inflected. 
The pedicle-valve has the rostrum produced and incurved, the 
apex slightly truncated by the subcircular foramen; deltidial 
plates small and obscure. The teeth are comparatively small, 
projecting forward and gently upward, free at their extremities 
and supported by narrow dental plates which join the bottom of 
the valve above the middle of its length and are continued for- 
ward as slender, widely divergent ridges upon the inner surface, 
gradually merging into the shell. 
/ 103 
