106 CARBONICOLA, ANTHRACOMYA, AND NAIADITES. 



posterior inferior angle, gradually diminishing in intensity as it passes in this 

 direction ; anterior to the oblique timidity the shell is flattened. Posterior to and 

 above the swelling the shell is compressed aud flattened into the hinge-line, the 

 flattened portion often being traversed by obscure radiating lines, especially well 

 marked in the young state. 



Interior. — Not known at present. 



/,'</, riur. — The surface is covered with lines and strise of growth, well marked 

 and distinct and crowded anteriorly, becoming almost obsolete posteriorly, so that 

 the posterior portion of the shell is almost smooth. The strise run parallel to the 

 inferior and posterior margins, and terminate above in the hinge-line somewhat 

 obliquely. The periostracum is wrinkled. 



Dimensions : 



Antero-posteriorly. Dorso-ventrally. 



Fig. 13, PI. XV, measures . 40 mm. 16 mm. 



Fig. 18, PI. XV „ . 30 mm. 10 mm. 



Localities. — North Staffordshire : the shale over the Bowling Alley Coal 1 at 

 Adderley Green, Bucknall, and Whitfield. Fulledge, Burnley. High up in the 

 Gannister series at Burrs, half a mile north of Bury, Lanes. Roof of Shale Coal, 

 Wakefield. 



Observations. — This species was founded upon a comparatively poor specimen 

 in the cabinet of Mr. John Ward, F.G.S., of Longton, by Mr. Salter, who, however, 

 published no description ; but this omission was made good by Mr. R. Etheridge, 

 F.R.S., in Mr. Ward's book on the ' Geology of the North Staffordshire Coal-field ' 

 (op. supra, cit.). This specimen I am able to figure on PL XV, fig. 14, by the 

 kindness of Mr. John Ward. As I pointed out in my redescription of this fossil 

 (op. supra cit.), Mr. Etheridge described the specimen with the preconceived idea 

 that the shell belonged to the Anatinida?, and that he mistook an imperfection for 

 a central umbo, and somewhat unwisely surmised the shell to possess character- 

 istics belonging to the genus Anatinidas, which could not be seen in a single 

 imperfect valve. The specimen is altogether too imperfect to serve as a specific 

 type, but I believe that enough has been left of it to show that the shell belongs 

 to a distinct species, of which T have been able to procure good examples. The 

 typical posterior cud of Mr. Ward's specimen is well preserved, and there can be 

 little or no doubt that it is a similar shell to PI. XV, fig. 13, from the Kay 

 Shuttleworth Collection of the Manchester Museum, Owens College, which 

 probably has attained a similar stage of growth. The other specimens from the 

 same Collection, PL XV, figs. 10, 17, ami 10, and the beautifully preserved 



1 Mr. Ward gives the Holly Lane seam, but I think it is more probably the Bowling Alley, 

 the next Beam above which is overlain by a shell-bed. The two seams are always worked together, 

 and the rubbish would be on the same tip. 



