ANTHRACOMYA MINIMA. 117 



Distribution. — Knowles Ironstone, Longton railway-cutting, south of Kidsgrove, 

 in North Staffordshire. Middle Coal-measures. Prestolee, near Manchester. 

 Black Band, Blaina, South Wales. Wylam Colliery, Northumberland. Scotland : 

 Possil ; Langton Burn, Dunse; Blackadder Water, Dunse. 



Observations. — When I gave the name A. minima to this shell in 1893 I was 

 unaware that the species had been named or described before. By a lucky 

 coincidence I was fortunate enough to hit on the same specific name as that given 

 by the earliest observer, R. Ludwig. It was the examination of his type 

 specimens at Dresden which convinced me of the identity of his shells, though 

 they were crushed, with the British forms. Unfortunately, too, his figures are not 

 good. At that time Professor Geinitz showed me some specimens labelled Modiola 

 uarlotta, Romer, which I could not distinguish from Anthracomya minima. 

 I have therefore placed Romer's name as a synonym. Romer thought his shell 

 had been previously described by Volpersdorf, who however, only gave it the 

 generic name of Modiola. 



Salter figures some small shells from the South Wales Coal-field, of whose 

 generic affinity he evidently did not feel quite sure, as he calls them Modiola or 

 Anthracomya. Judging from figures only, I think it probable that two of his 

 specimens (figs. 1 and 2, not 3) may be referred to A. minima. 



The general form of A. minima closely resembles that of A. Phillipsii, but it is 

 much smaller ; and owing to the fact that the latter shell nearly always occurs 

 crushed, it is next to impossible to make out accurately many of its characters. 

 The two forms were very gregarious in habit, and are found in large numbers in 

 certain beds, but as far as I know not together ; other species and genera are 

 conspicuously absent, with the possible exception to be noted below. Still there 

 is nothing antagonistic to the view that one was only a dwarfed form of the other. 



There often occurs both in Staffordshire and Lancashire, in a bed with 

 A. minima, a form to which I gave the name Anthracomya carinata, and it would 

 appear on comparing it with a typical specimen of the former to be quite distinct ; 

 but a series of intermediate forms occur which completely connect the two. I 

 have, therefore, now placed A. carinata as a variety of A. minima. There is a 

 resemblance also between our shell and the forms called on the Continent Unio 

 carbonarius, Bronn, and Unio Goldfussianus, de Koninck. It is very difficult to 

 form any conclusions as to what shells are represented by these names, owing to 

 the disappearance of all the types, and the inaccuracy of authors, to which 

 Professor Geinitz drew attention in a paper in « Neues Jahrbuch ' for 1864, 

 p.. 651. In the ' Petrefacta Germanica,' p. 181, pi. cxxxi, fig. 20, Goldfuss 

 o-ives a figure of Unio uniformis, Sowerby, which, as de Koninck pointed 

 out in his remarks on Carolinia ovalis in his ' Animaux fossiles du bassin 

 Carbonifere de la Beige,' p. 74, is totally distinct from Sowerby's shell, and he 



