274 APPENDIX TO THE 



Khynchonella Wettonensis, Dav. Plate LV, figs. 1 — 3. 



Sj). Char. Shell transversely oval, wider than long ; ventral valve more convex than the 

 dorsal one, with a mesial fold of greater or lesser elevation, commencing at about the 

 middle of the valve, and extending to the front ; beak small, angular, but slightly produced, 

 and incurved with a minute circular foramen, placed under its extremity. Dorsal valve 

 moderately convex, with a sinus of greater or lesser depth, commencing close to the 

 extremity of the nmbone, and extending to the front, where it attains its greatest breadth 

 and depth. Each valve is ornamented with small, radiating ribs or striae, while numerous 

 concentric lines of growth occur at irregular intervals on the surface of the valves. Interior 

 unknown. 



Average dimensions: length 8, width 11, depth 5 lines. 



Obs. This Rhynchonella is at once distinguishable from all its congeners in the 

 Carboniferous period on account of its peculiar shape and character, occasioned by the fold 

 existing in the ventral valve and the sinus in the dorsal one. This arrangement is, how- 

 ever, known to exist in some Devonian, Jurassic, and Cretaceous Rhynchonellae, but is not 

 of common occurrence. In very young specimens the fold and sinus are but slightly marked, 

 but they become very apparent and developed with age ; the strise also in some aged 

 examples are hardly visible, but are well marked in the larger number of specimens. 



This remarkable shell occurs by myriads in the Carboniferous Limestones at Narrow- 

 dale, in the parish of Allstonefield, not two miles from Dove, in Staffordshire, and is one 

 of Mr. Carrington's most interesting discoveries. 1 



Productus Carringtoniana, Dav. Plate LV, fig. 5. 



Sp. Char. Shell somewhat sub-orbicular or transversely semicircular, wider than long ; 

 hinge-line straight, and about as long as the width of the shell ; ventral valve regularly 

 and evenly convex ; beak small, hardly produced beyond the hinge-line j ears small ; 



1 In a letter dated lltli September, 1862, Mr. Carrington writes, "I had a fortunate find yesterday, 

 having been quarrying for several days on a hill side to the depth of three feet, I arrived at a fault which 

 originally bad been an open cleft in the ocean bed. This bed had been filled with materials differing from 

 the sides which bounded the cleft. The fossils were peculiar, consisting of thousands of closely packed 

 specimens of Linyula mytiloides, Diseina nitida, Rhyn. Wettonensis (Dav., n. sp.), Productus Carring- 

 toniana (Dav., n. sp.), and of a large variety of Spiri/era Carlukiensis (Dav.) ; and it would appear to me 

 that the cleft had been perpendicular at the time of their existence, as it is now (?), and that the 

 Bracbiopoda must have been attached to its sides, as the great abundance of the specimens are found in a 

 conglomerate of one inch or more all the way down. The small Spirifer occurs by myriads, and there are 

 also some fine Pecten^ In the limestone bounding the cleft we find Prod, gigcniteus, P. striatus, 

 Bellerophon, Nautilus, &c." 



