Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/175

 1869.]. DAVIDSON PEBBLE-BED BEACHIOPODA. 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 Eotjaoxti, n. sp. PI. 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. Strophomena Etheridgii, n. sp. PI. 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 above 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 Rhynchonetta ovalis in the same pebble.