Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/176

 30. Strophomena Edgelliana, n. sp. Pl. VI. figs. 2-5.

Transversely semicircular, with expanded angular extremities; hinge-line as long as the greatest breadth of the shell ; ventral valve slightly convex, area narrow, divided in the middle by a triangular fissure ; dorsal valve very slightly convex, almost flat ; surface of valves marked by numerous small bifurcating striae. In the interior of the ventral valve there is a small tooth on either side at the base of the fissure, while the muscular impressions form a small saucer- shaped depression surrounded by a raised margin ; this depression is about as wide as long, or about one-fourth of the width of shell, notched in front, and divided along the middle by a broad angular ridge. In the interior of the dorsal valve there exists a small bilobed cardinal process. Slightly projecting deviating socket-ridges are also visible. Under the cardinal process a raised hollow roof-like ridge extends to a little distance, prior to becoming forked ; on either side of this ridge are situated the muscular scars. Length and breadth 11 lines.

Several internal casts, as well as external impressions of this interesting species have been found by Mr. Vicary associated with specimens of an Orthis resembling O. redux; consequently, if this last identification proves correct, S. Edgelliana would be of Silurian age. It bears, however, a good deal of resemblance to the Devonian Leptoena Dutertrii (Murch.), both in external shape and internal arrangements ; but it differs sufficiently from this and O. redux to justify us in proposing for it a distinct specific designation. I have named it after Mr. Arthur Edgell, to whom we are indebted for the discovery of several interesting Budleigh specimens.

31. Strophomena Vicaryi, n. sp. ? Pl. VI. figs. 6 & 7.

Shell transversely semicircular, regularly convex, with expanded angular extremities ; hinge-line straight and long, with closely set perpendicular or slanting striae ; area narrow, divided by a triangular fissure ; the muscular scars form two elongated depressions, divided by a raised mesial ridge ; external surface marked by numerous thread-like striae, two or three finer ones being placed between each pair of the larger striae ; dorsal valve not known. Length 8, breadth 11 lines.

Of this species we are at present acquainted with one valve only ; and consequently a complete description of the shell cannot be drawn up. The shape of its muscular impressions, in the ventral valve, differs from that seen in S. Edgelliana. Mr. Salter has also expressed the opinion that the two are specifically distinct. It has been found by Mr. Vicary in company with S. Etheridgii and Rhynch. ovalis ; its real age cannot, however, be at present accurately determined.

32. Strophomena budleighensis, n. sp. ? P1. VI. fig. 1.

Of this species a remarkable internal cast of the ventral valve only has been found. It is convex, semicircular, and about as wide as long ; the hinge-line as long as or a little longer than the width