61 



Rhinobolus. 

 (Species uncertain, but perhaps a var. of H. Galtensis.) 



Plate 9, figs. 2 and 2 a. 



' Pedicle valve. Exterior coinpreased convex, subovate in marginal out- 

 line, about one-third longer than broad, broadest a little in advance of 

 the midlength and rather abruptly pointed behind, its surface marked 

 with concentric lines of growth at irregular but somewhat distant in- 

 tervals. Interior shallowly concave, the concave portion a little longer 

 than broad. Beak elevated, solid, erect : cardinal area or pedicle surface 

 a little broader than high, occupying about one-fourth of the length of the 

 valve, its interior margin convex and slightly produced in the centre and 

 concave on each side. " Deltidium " gently convex, moderately promin- 

 ent, much higher than broad and striated across: "deltidial ridges" 

 broad, not so much raised as the " deltidium " and almost flat :" areal 

 borders " consisting of a pair of widely divergent narrow and acute 

 angular ridges, which are separated from each of the deltidial ridges by a 

 linear groove. " Umbo-lateral scars " represented by a pair of distant, 

 small and indistinctly defined shallow pits. Crescent much like that of 

 Trimerella, but with its sides more nearly marginal. Platform apparently 

 essentially similar to that of S. Galtensis, but placed a little farther 

 forward. 



Brachial valve. Unknown, 



Length, forty-eight millimetres ; greatest breadth, thirty-two mm. ; 

 maximum thickness of test, eight mm. 



Irvine Bocks, Elora, at the " cave * near Modeland'a foundry, J. 

 Townsend, 1885 ; a nearly perfect and well preserved specimen of the 

 pedicle valve, with the test preserved and showing the whole of the 

 characters of both the inside and outside of that valve, though the front 

 margin of the platform is slightly broken. 



This shell has a much shorter cardinal area or pedicle surface than that 

 of the pedicle valve of JR. Galtensis, but it may possibly represent only an 

 extreme variety of that species. 



Orthis. 



A few casts of the interior of single valves of apparently two species of 

 Orthis have been collected at Durham, but they are all much too imperfect 

 and too badly preserved for identification or description. 



Strophomena. 

 Elora, T. C. Weston, 1867 : a coarse cast of the interior of the convex 

 valve of a species of this genus, which is also much too imperfect to be 

 identified. 



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