CRITICAL BIBLIOGRAPHY. 21 
many of their names are synonyms, it being highly probable that many of these 
species are only varietal forms, or young. It is to be remarked that no mention 
is made by de Ryckholt of de Koninck’s or any other person’s previous work on 
the subject, save only one single specimen after Goldfuss. 
1849. In 1849 Capt. T. Brown issued his ‘ Fossil Conchology,’ in which he 
re-figured all those shells previously described and figured in the ‘ Ann. and Mag. 
Nat. Hist.’ (op. supra cit.) he also gave copies of the figures of those Coal-measure 
forms figured and described by J. De Carle Sowerby (op. supra cit.), also of one 
form figured by Rhind, and those from the ‘ Mineral Conchology,’ and in addition 
he described and figured Unio littoralis and U. discrepans from Low Moor, Bradford ; 
Avicula modioliformis, Water of Leith (Naiadites). 
Modiola Williamsoni, Wakefield (Anthracomya), pl. Ixxi, figs. 24, 25. 
a subtruncata, Wakefield (Naiadites), pl. lxxii, figs. 15, 16. 
3 curtata, Wakefield (Anthracomya), pl. Ixxu, figs. 19, 20. 
»  Robertsoni, Newcastle-on-Tyne (Anthracomya), pl. Ixxii, figs. 24, 25. 
* Moorei, Vale of Todmorden (Anthracomya), pl. Ixxii, fig. 27. 
Bp minuta, Low Moor (?), pl. lxxii, fig. 29. 
He drops the name Pachyodon, and returns to the old name Unio. 
1851. J. W. Binney (‘ Manchester Lit. Phil. Soc. Trans.,’ vol. x, p. 181, pl. 1, 
figs. 1, 2; pl. ii, fig. 1) published a paper on some trails and holes found in 
Carboniferous strata which he thought might be due to molluscs, probably 
Modiolx, from the shape of their casts. 
1852. F. A. Quenstedt, referring in his ‘ Petrefactenkunde’ to Coal-measure 
Unios, describes a “ glatter Leiste unter der Ligament.” (He figures Anodonta 
lettica, Quenstedt, pl. xliv, fig. 16, from the Lettenkohle of Gaildorf, which from 
its shape would appear to be Naiadites.) 
1853. Isaac Lea, in his paper “‘On some New Fossil Molluses in the Carbo- 
niferous Slates of the Anthracite Seams of the Wilksbarre Coal-formations,” 
published in the ‘ Journal of the Academy of Natural Science of Philadelphia,’ 
ser. 2, vol. ii, pt. 3, January, 1853, p. 203, pl. xx, figs. 1 and 2, describes and 
figures two new species of Modiola. M. Wyomingensis and M. minor, which 
occur with shells, which he provisionally places under Posidonia, and certain fish 
remains. M. Wyomingensis has apparently all the external characteristics of 
Naiadites, and, indeed, Lea compares his shell with Modiola (Naiadites) carinata, 
Sow. The figure of M. minor is that of a shell too fragmentary for comparison. 
1854 and 1856. In 1854 McCoy (‘ British Paleeozoic Fossils,’ by A. Sedgwick 
and F. McCoy, p. 514) proposed the name Carbonicola for the Coal-measure 
Unios. Referring to King’s proposed name Anthracosia, but supposing that 
King had given up his intention to make use of it (as he had not published 
anything further) McCoy gave a description. 
