1869. ] _ DAVIDSON—PEBBLE-BED BRACHIOPODA. 85 
Besides the species of Orthis above recorded, Mr. Vicary has sent 
me two or three impressions and internal casts, which cannot be 
referred to any of those above enumerated. The material was, 
however, too scanty and incomplete to warrant our attempting 
specific identifications. 
28. StropHomena Rovavtri, n.sp. Pl. VI. figs. 8 & 9. 
Shell semicircular, slightly wider than long ; hinge-line straight, a 
little less than the width of the shell. Ventral valve very moderately 
convex, with a narrow area and open fissure. Dorsal valve almost 
flat, or very slightly concave. Exterior finely striated. In the 
interior of the ventral valve a small hinge-tooth is situated on either 
side of the base of the fissure, while the muscular scars form a large 
saucer-shaped depression laterally margined by a slightly elevated 
ridge. In the interior of the dorsal valve a wide raised border sur- 
rounds the shell; hinge-area linear. The cardinal process is com- 
posed of two testaceous projections, under which are located two 
elongated, parallel muscular impressions, surrounded by a narrow 
elevated ridge, and separated along the middle by a rather wide 
interspace. Length 10, width 11 lines. 
This species appears to be rare, only a few internal casts of the 
two valves having been found by Mr. Vicary. As no other Brachiopod 
has occurred along with it, I cannot say whether it should be re- 
ferred to the Silurian or to the Devonian series. In external form 
it bears much resemblance to more than one Silurian as well as 
Devonian species; but the shape of the muscular impressions in the 
dorsal valve seems to distinguish it from described species of the 
genus. 
29. SrropHomena Eruerivent, n. sp. Pl. VI. figs. 10-12. 
Semicircular, as wide as or rather wider than long; hinge-line a 
little shorter than the width of the shell; ventral valve very slightly 
convex ; area narrow, muscular impressions forming a large saucer- 
shaped depression, laterally margined by a slightly raised border, 
and longitudinally divided along the middle by a narrow ridge. In 
the interior of the ventral valve the hinge-area is linear, with a 
minute cardinal process in the centre; under this is situated a small 
oval-shaped depression, with another smaller pit on either side, while 
beyond these may be seen the small hollow for the reception of the 
teeth of the ventral valve. Under the three central depressions 
aboye described there exists a short, raised mesial ridge, broad at 
its origin, but becoming gradually attenuated as it approaches its 
anterior termination ; between this and the hinge-line are seen two 
granular ovarian elevations. ‘The muscular impressions are indis- 
tinct. External surface not known, in all probability finely striated. 
Length 11, width 12 lines. 
Of this interesting species I have seen but two internal casts. It 
was found by Mr. Vicary along with S. Edgelliana; but I am uncer- 
tain as to its real age. Mr. Vicary believes that he has found 
Ehynchonella ovalis in the same pebble. 
