^0^' 55'] CAEBONirEROUS LAMELLIBEANCHIATA. 365 



23. Gn Three new Species of Lamellibranchiata from the 

 Carbonifeeotjs Rocks of Great Britain. By Wheelton Hind, 

 M.D., B.S., F.E.C.S., F.aS. (Read April 26th, 1899.) 



[Plate XXY.] 



I. On a new species of Anthracomya, from the Upper Coal 

 Measures of North Staffordshire. 



Introduction. — In my monograph on Carhonicola, Anthracomya^ 

 and Naiadites ^ I pointed out that only one lamellibranch was then 

 known to occur in the Upper Coal Measures of North Staffordshire, 

 and indeed of Great Britain. The comparative sections illustrating 

 the distribution of the Lamellibranchiata in the various coalfields 

 showed that in a large number of them the highest known lamelli- 

 branch was Anthracomya Phillijjsii, and that this species might well 

 be considered characteristic of a certain zone. Since the date of that 

 publication I have been able to accumulate material from a series 

 of beds in the North Staffordshire and Lancashire coalfields much 

 higher than the A. Philli^sii-zone, which contains a hitherto unde- 

 scribed fossil shell, evidently referable to the genus Anthracomya. 

 This species appears to characterize also a certain somewhat narrow 

 zone of calcareous shales and freshwater limestones which occur 

 towards the top of the Coal Measures in these localities. The shells 

 from Pallowfield were collected by Mr. Reader. They are free from 

 the matrix, and, although often fragmentary, afford distinct details of 

 the hinge. I am not sure whether Ihere are not at least two distinct 

 species from the Pallowfield beds, but hesitate to erect a new species 

 on mere fragments. 



Anthracomya calcifera, sp. nov. (PI. XXY, figs. 14-20.) 



Specific Descriptio n. — Shell small transversely, modioliform, 

 very inequilateral, gibbose, expanded and flattened posteriorly, 

 oblique. The anterior end is very short, and narrower than the rest 

 of the shell, and its border is eUiptically curved. The inferior border 

 is produced downward and backward, and is almost straight, sub- 

 parallel with the superior border. The posterior border is com 

 paratively lengthened obliquely, truncate from above downward 

 and backward, and is straight for the greater part of its extent, 

 but joins the inferior border at a somewhat rounded angle. 



The hinge-line is straight, much shorter than the inferior border, 

 and the posterior superior angle is weU marked and obtuse. The 

 umbones are small, pointed, incurved, and contiguous, placed in the 

 anterior quarter of the shell. 



Passing downward and backward from the umbo towards the 

 posterior inferior angle is a well-marked, bluntly rounded fold, in 

 front of which the valve is obliquely compressed, and posterior to 



1 Palseont. Soc. pt. ii, vol. xlix (1895) p. 156. 



