58 CARBONICOLA, ANTHRACOMYA, AND NAIADITES. 



it ; in the left valve a split cardinal tooth, which receives between its two halves 

 the tooth of the opposite valve ; anterior and posterior laterals are absent. In the 

 figure will be noticed a faint oblique line on the posterior part of the hinge-plate, 

 which, with a similar occurrence in PI. VI, fig. 2, are the only indications of 

 horizontal lateral teeth that I have met with. PI. V, fig. 38, contains a small 

 pearly nodule, well shown at "a" in the drawing. 



That this form of hinge-plate (y) is not confined to 0. ovalis is certain, I think, 

 from the occurrence of a similar form in specimens having the typical shape of 

 C. acuta. 



Prof. Amalizky 1 has referred a new species of his, named Anthracosia subnucleus, 

 from the Permian formation of the Oka Volga Basin, as allied to the forms — 

 U. ovalis, Martin ; U. centralis, Sow. ; U. uniformis, Sow. ; U. nucleus, Brown ; 

 and U. ovalis, Salter. Judging, however, from the figures, dimensions, and 

 description, his shell is totally different from the form under discussion, and I 

 have shown above that the forms referred to are themselves very different, one of 

 them being from the Oolite. 



Localities. — England : Tupton Moor and Staveley. Roof of the Cockshead 

 Seam and the Cockshead Rock, Lower Coal-measures of North Staffordshire. 

 Pennystone Beds, White Flats, Blue Flats — Coalbrookdale. Butterley, Leicester- 

 shire. Old Coal, South Wales. Scotland : Kenmuir and Clyde Pits, Lanarkshire 

 Coal-field. 



5. Caebonicola Polmontensis {Brown). PI. VII, figs. 1 — 4. 



Unio (from Coal-shale), Bhind. Age of the Earth, pi. ii, figs, c, d. 

 — Polmontensis, Brown. Foss. Conch., pi. lxxiii, figs. 32, 33. 



Specific Characters. — Transversely elongate-oval ; sides flatly convex. Umbones 

 are much elongated transversely, narrowed, apart, and everted anteriorly, situated 

 at two-fifths of the length of the shell from the anterior end, which is rounded. 

 The posterior end is compressed and bluntly pointed. The hinge-line is straight, 

 and in casts median. The interior of the shell shows fine striae radiating from the 

 umbones to the surface. Posterior slope obtusely rounded ; upper surface 

 expanded. There is an oblique, shallow, broad depression on the sides of the 

 shell, most marked towards the posterior part of the inferior border. External 

 characters unknown. Muscular scars normal. Pallial line not very far from the 

 margin of the shell. 



1 ' Palseontographica,' vol. xxxix, 1892 ; ' Ueher der Anthraeosien die Perm-formation Eusslands,' 

 156, pi. xx, figs. 19, 20. 



