ANTHRACOMYA VALENCIENSIS. 113 



the V-shaped arrangement of the wrinkles is at right angles to that which obtains 

 in the left valve, and that the condition is purely accidental. Mr. Salter says of 

 this shell (loc. supra cit.), " The general appearance is that of an ordinary convex 

 Modiola ; but the epidermis, deeply wrinkled V-fashion over the posterior slope, 

 shows its true affinity." He goes on to say, relying on this qua si-affinity to 

 Myadse which he allowed to overbalance the evidence afforded by shape, " We 

 cannot get at the interior, but there is not much doubt that there is a pallial sinus, 

 and there were probably long siphonal tubes covered by a thick epidermis, the 

 animal burrowing in the mud as most of the Myadas do " — a condition which 

 subsequent investigation has shown to be absent. It was only under the head of 

 A. senex that any observations are made with regard to the generic affinity of 

 Anthracomya, and it is probable that the wrinkled periostracum of A. senex was 

 the chief factor in referring this genus to the Myadas. I have on this account 

 gone into the details given by Mr. Salter, and have quoted fully from his remarks. 

 A. senex is a rare shell, and I have only met with one other specimen from South 

 "Wales, also in the collection of the Geological Survey, but have obtained a few 

 from the Hard-mine and Cockshead Ironstone of North Staffordshire, but in these 

 beds it appears to be very rare. This species is easily distinguished from all 

 others by its oblique wedge-shaped gibbose form, and by the raised hinge-line 

 posteriorly and strongly marked diagonal keel. 



11. Anthracomya Valencibnsis, It. Etheridge, jun., nov. sp. Plate XVI, 



fiffs. 44—48. 



'e 



Specific Characters. — Shell small, pisiform, tumid. The anterior end is small, 

 regularly swollen, and has a convex border. The posterior end is expanded and 

 compressed with a bluntly convex border. The inferior border is almost straight, 

 passing with a gradual curve in front and behind into the anterior and posterior 

 borders. The hinge-line is straight, elevated posteriorly, somewhat shorter than 

 the greatest antero-posterior measurement of the shell. The umbones are small 

 and inconspicuous, slightly raised above the hinge-line, and non-contiguous. The 

 shell is evenly swollen in an oblique direction, the swelling being soon lost on the 

 surface of the shell. 



Interior. — Not known. 



Exterior. — The surface is covered with fine lines and strise of growth which 

 run parallel to the anterior inferior and posterior borders. The periostracum is 

 wrinkled. 



15 



