78 CARBONICOLA, ANTHRACOMYA, AND NAIAUITES. 



this species may be of value in denoting a definite horizon. I have found it to 

 occur all round the basin, from Hulme Colliery on the south-west, along the 

 outcrop north-east to the foot of Mow Cop, and south-west by Talk-o'-th'-Hill 

 to Halmerend ia a bed some little way above the Cockshead Rock. Though found 

 to have a fairly wide horizontal distribution, it does not appear to occur at 

 more than one horizon. Although in no one specimen is the whole of the hinge- 

 plate to be seen, yet, from many specimens where portions of it are to be seen, it 

 appears to have a fairly regular character, resembling that of Carbonicola robusta. 

 Portions of the hinge are seen in PL XI, figs. 15, 25, and 26. 



The figure of TJnio Castor, Eichwald, ' Lethaea Rossica,' 1855-9, pi. xxxix, 

 fig. 20, somewhat resembles the species under description ; but the latter is from 

 beds of Permian age, and I have not been able to compare the shells, so that I 

 cannot say whether the species are the same ; but certainly Brown's name has 

 the priority. 



Prof. Amalizky (' Palseontographica,' vol. xxxix, " Ueber die Anthracosien der 

 Permformation Russlands," pi. xxii) gives figures of Naiadites xubcastor. nov. 

 sp., figs. 30 — 33 ; Naiadites Fischeri, nov. sp., figs. 34 to 39 ; and Naiadites Castor, 

 figs. 40 to 43, — all of which show some resemblance to the adult forms of 

 C. similis. 



Captain Brown's description is as follows : — " Compressed, anterior side 

 rounded ; umbones hardly produced, contiguous ; posterior side parallel, obliquely 

 truncate; hinge-line straight, basal line arcuated; surface with transverse 

 wrinkles." Both the shells TJnio similis and TJnio nanus are from the same locality 

 — Middleton, near Leeds. 



De Koninck gave the specific name Cardinia nana to a small fossil which 

 Prof. Geinitz considers to be the same as that figured later on by Ludwig as 

 Cyclas nanus ; and he states that the fossil in question is an Estheria, and proposes 

 that both should be placed in that group under the name of Estheria nana (' Neues 

 Jahrbuch fur Mineralogie,' &c, 1864, pp. 653-4 ; see above, p. 17). 



Specimens of Cardinia Scherpenzeeliana (de Ryckholt, 1850) approach, very 

 closely in form the young of Bronn's species, e.g. PI. XI, figs. 10, 11, 13. 



15. Carbonicola cuneiformis, sp. nov. Plate XI, figs. 24, 24 a. 



Specific Characters. — Shell very oblique, moderately convex, wedge-shaped. 

 The anterior end is small and compressed, but broad above. The shell rapidly 

 becomes swollen in a posterior direction, and after attaining the maximum 

 convexity is gradually compressed into the posterior border. 



The anterior border terminates abruptly above, forming a rounded slightly 



