86 PROCEEDINGS OF THE GEOLOGICAL SOCIETY, (Dec. 8, 
30. SrropHomena Epeentrana, 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 strize. 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 sancer- 
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-hke 
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 hig 
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 
Leptena Dutertric (Murch.), both in external shape and internal 
arrangements; but it differs sufficiently from this and O. redus 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. SrropHomEena Vicaryt, 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 strie; area narrow, divided by a trian- 
gular fissure; the muscular scars form two elongated depressions, 
divided by a raised mesial ridge; external surface marked by nume- 
rous thread-like striz, two or three finer ones being placed between 
each pair of the larger strie ; 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. Hdgelliana. Mr. Salter has also expressed 
the opinion that the two are specifically distinct. It has been found 
by Mr. Vicary in company with S. Etheridgi and Rhynch. ovalis; its 
real age cannot, however, be at present accurately determined. 
32. SrROPHOMENA BUDLEIGHENSIS, n. sp.? Pl. 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 
