CRITICAL BIBLIOGRAPHY. 17 



Of the remaining shells named Unio, Nos. 9 and 10 are now referred to 

 Anthracomya (Salter), Nos. 11 to 14 to Garbonicola (M'Coy), while Nos. 15, 16, 17, 

 and 18, described as Modiola, Mytilus, and Avicula, are now referred to Naiadites 

 (Dawson). The figures are good and very typical, except in the case of Garbonicola 

 robusta and Anthracomya dolobrata, which are from imperfect specimens. 



1842. In 1842 S. Stutchbury ('Ann. and Mag. Nat. Hist.,' vol. viii, p. 481) 

 proposed the name Pachyodon for certain Liasic and other shells which possessed a 

 peculiar hinge-tooth, but he did not include any Coal-measure shells under this 

 denomination ; and it was from external appearance only that later on Captain 

 Brown considered that the Coal-measure Unios might belong to this genus. 



1842. In 1842 appeared Agassiz' translation of Sowerby's ' Mineral Conchology,' 

 in which he proposed the name Cardinia for the shells of the Coal-measures pre- 

 viously described as Unios, considering them to be related to certain Jurassic forms. 



About the same year (1842) de Koninck described and figured nine forms in 

 his ' Des animaux fossiles du bassin Carbonifere de la Beige,' only one of which 

 (Cardinia nana), which Geinitz thinks 1 belongs to Esther ia, was mentioned for the 

 first time. I am told by Professor Dewalque. of Liege, that these specimens are in 

 the museum of Cambridge, Massachusetts. They are as follows : 



Cardinia acuta. 



,, subconstricta. 

 ,, atrata. 

 ,, robusta. 

 „ phaseolus. 



He follows Agassiz in referring these forms to Cardinia, and describes the 

 shell in such a manner that it is evident he never saw an interior of a Coal-measure 

 shell, and that he took his type from Jurassic specimens. The figure of Cardinia, 

 robusta is remarkable, and has apparently been drawn from Sowerby's type, 

 which, however, is incomplete, so that the lines of growth terminate abruptly ; 

 but in the Belgian form the lines of growth are carefully curved upwards to end, 

 as if naturally, in the posterior slope. 



This form is not mentioned by any Continental author by name, and is only 

 figured by Achepol under a different title, 2 and in that case is found in a different 

 coal-field. De Koninck's figure of Cardinia carbonaria is very different from Unio 

 carbonarius, Bronn, to which it is referred. 



1843. Colonel Portlock, in his ' Geological Report on Londonderry,' p. 568, 

 mentions a shell described as Unio ? figured pi. xxxviii, fig. 6, as a doubtful shell 

 with a deep impression near the beak. It is, however, associated with marine shells, 



1 'Neues Jahrbuch f. Min.,' &c, 1864, p. 654; see also 'Eeport British Association' (for 1887), 

 1888, pp. 68 and 69, where Ludwig's Permian Cyclas nana (1861) and de Koninck's Upper 

 Carboniferous Cardinia nana (1842), which are distinct forms, are referred to the genus Estheria. 



2 Vide infra. 



3 



Cardinia 



nana. 



» 



abbreviata. 



)» 



tellinaria. 



>> 



carbonaria 



>> 



ovalis. 



