SOLENOPSIS PARALLELA. 415 



Vise differs from that of S. pelacjicus, Golclfuss ; but, on the other hand, he 

 thinks it does not belong to 8. minor. I am of opinion, however, that it is the full- 

 grown example of this species. 



Baily {op. cit.) gives a figure of a small example of this species from 

 King's Co. He says the beds consist of " dark blue shales with limestone bands 

 full of shells, the blue shales containing bivalve shells;" and he states that 

 Nuculana attenuata and Sanguinolites plicatus, and a shell which I refer to 8. 

 roxburgensis, occur witli it. PI. LI, fig. 4, is a specimen from the lowest bed of 

 limestone but one in the Shap district, and I take it to be a full-grown specimen 

 (a cast of the interior) of 8. minor. This specimen shows the anterior adductor 

 muscle-scar and a groove to receive the thickened hinge-plate. The absence of 

 oblique ridge, and the sulcus beneath the umbo, separate this shell from 8. pelagicus, 

 Goldfuss, with which it agrees more in size than any specimen previously figured 

 from British Carboniferous rocks. 



SoLENOPSis PAEALLELA, sp. uov. Plate XLIV, fig. 10; Plate LI, figs. 2, 2 a. 



8pecific Characters. — Shell below medium size, compressed and flattened, very 

 inequilateral, dorsal and ventral margins almost parallel ; posterior end not 

 narrowed ; anterior end very short, compressed ; almost as deep from above down- 

 wards as the posterior end; its margin rounded; passing with a regular curve into 

 the inferior border, which is straight and very long, meeting the posterior border 

 at a bluntly rounded angle. The posterior border is oblique, truncate from above 

 downwards, almost straight, making a well marked but slightly obtuse angle with 

 the hinge-line. The superior border is straight and elongate. The umbones are 

 small and inconspicuous, compressed, directed forwards, scarcely elevated, and 

 placed very far forwards. A very obscure oblique line passes downwards and 

 backwards from the umbo to the posterior inferiorjjangle, separating a com- 

 paratively large flattened dorsal slope from the rest of the valve, which is 

 regularly but very gently convex. 



Interior. — The anterior adductor muscle-scar large, well marked, triangular in 

 shape, and placed in the anterior and upper part of the umbonal hollow, remote 

 from the margin ; the posterior is very shallow and inconspicuous, mantle-line 

 entire. The interior of the shell shows fine and close lines of growth, "which 

 terminate at the oblique line ; the hollow of dorsaKslope shows flattened obsolete 

 grooves and ridges. In front, fine radiating strioe pass from the umbones towards 

 the lower border. Hinge edentulous posterioi'ly, with a rolled thickened margin, 

 leaving a groove in casts. 



