La MELLIBRANCHIATA. | LOWER PALAZEZOZOIC MOLLUSCA. 269 
MopIOLOPSIS SOLENOIDES (Sow. Sp.) 
Syn. and Ref. = Cypricardia? solenoides Sow. Sil. Syst. t. 8. f. 2. 
Sp. Ch.—Subcylindrical ; dorsal and ventral margins subparallel; length two and half to three times the 
width, which is greatest from the beak to opposite margin; gently convex; posterior slope slightly convex, 
defining a slightly arched obtuse ridge from the beak to the posterior inferior angle; anterior end a little 
contracted below the beaks, elliptically rounded, one-seventh to one-eighth of the length; posterior end very 
oblique, subtruncated, elliptically pointed, the end obtuse; hinge-line not elevated at the end; ventral margin 
nearly straight, slightly concave ; a little clavicular internal ridge from the beak to the posterior edge of the 
anterior adductor. Length one inch three lines, greatest proportional width (from beak to opposite ventral 
margin) =, depth of one valve about jj. 
The greater proportional length, the hinge-line not being elevated, the narrow and more obliquely trun- 
cated posterior end, and greater convexity, distinguish this from the allied varieties of the M7. complanata (Sow. 
sp.). The Leptodomus amygdalinus (Sow. sp.) to which Mr Sowerby likens it, is distinguished by its much 
greater gibbosity, its shorter wedge-like outline (Mr Sowerby’s figure being unusually elongate from pressure), 
broad, subtruncate anterior end, with its deep lunette, Ge. 
Position and Locality —Common in the hard, green, micaceous flags of the Upper Ludlow of Benson Knot, 
Kendal, Westmoreland ; also in the yellowish micaceous tilestone of Storm Hill, Llandeilo, Caermarthenshire. 
Genus. DOLABRA (M°Coy). 
Gen. Char.—Obliquely ovate, gibbous ; left valve larger than the right ; beaks large, obtuse, nearer the 
anterior than posterior end ; hinge-line shorter than the shell, extending in a right line each side of the beaks 
(appearing crenulated in some species) ; a flat, narrow, ligamental area the length of the hinge-line, widest 
between the beaks; anterior end narrower than the posterior, rounded, no byssal sinus or furrows; ventral 
margin slightly convex ; posterior end obliquely truncated; posterior slope flattened, defined ; surface smooth or 
finely striated; one thick, elongate, posterior lateral tooth or cardinal ridge in each valve, inclining at an acute 
angle from the hinge-line, that of the left valve sometimes bifid ; anterior adductor impression ovate, superficial ; 
pallial scar entire ; posterior adductor moderate, irregularly rounded, superficial. 
I am not certain of the nature of the obscure crenulations observed on the hinge-line of some species ; if 
they be found to resemble those of Arca, the genus is still perfectly distinguished therefrom by the long, thick, 
diverging, posterior tooth within or beneath them, resembling almost exactly in fact the posterior teeth and 
hinge-crenulations of Gervillia, illustrating the suggestion of Phillips, that Dolabra was allied to Lyrodesma 
or Actinodonta, in which the cartilage sinus seems to have been similarly divided; some species have clearly 
entire (not crenulated) cardinal edges. The genus seems to me intermediate between Leptodomus and Edmondia, 
but without the anterior lunette of either of those genera, but apparently having the thick cardinal ridges and 
strong shell of the latter. 
Dorapra ELLIPtica (M/‘Coy). Pl. 1. L. fig. 10. 
Ref—Id. M*Coy, Ann. Nat. Hist. 2nd Series, Vol. VII. p. 52. 
Sp. Ch.—Elongate, elliptical, length slightly more than twice the width; beaks obtuse, moderate, one- 
sixth of the length from the anterior end; anterior end small, elliptically rounded; ventral margin slightly 
conyex ; hinge-line slightly elevated ; posterior end obliquely rounded; valves moderately convex ; diagonal 
ridge very obtusely rounded, posterior slope steep, but not abruptly flattened ; surface apparently marked with 
fine lines of growth. Length one inch six lines, width from beak to opposite margin eight lines, width from 
ventral margin to end of hinge-line about the same, depth of one valve three lines. 
The specimen described shews that in the left valve there were no other teeth but the thick, elongate, 
posterior one or ligamentary ridge, which is about a line below the hinge-margin. 
