ANTHRACOMYA WILLIAMSONI. 101 



was given by Professor Sir G. W. Dawson to a shell then named by him Naiadites, 

 but now recognised as Anthracomya (' Q. J. G. Soc.,' vol. 1, p. VS7, pi. xx, 

 figs. 7 — 10), but of a totally different species from that under discussion. 



Judging from the description and figure of Eichwald's Anodonta (Modiolopsis) 

 tenera, it is possible that it may turn out to be identical with A. Williamsoni, 

 and this author's description of the form is as follows :— " Sehr diinn, aber 

 weniger flach, sondern eher gewnlbt und concentrisch gestreift, das eine Bnde 

 weit breiter, als das andere mehr zugerundete, der wirbel flach, wenig hevorste- 

 hend der schlossrande grade; beide Schalen hangen durch das Schloss von dem 

 einen Ende bis zum andern zusammen wie dies bei Anodonten der Fall zu sein 

 pflegt ; " but it is impossible to be certain, without an examination of the shells, 

 whether Modiolopsis tenera belongs to Anthracomya Williamsoni or A. Wardi, which 

 it seems to resemble in its posterior border. I am strongly of the opinion that 

 one of these two species will be found to belong to Eichwald's form, and in that 

 case his name will have the priority. But there is still another uncertainty as 

 to the name, for it is also possible that the species under description may be 

 shown to be identical with Mytilus {Modioli) Teplofi, Murchison, de Keyserling, 

 and de Verneuil, ' Paleontologie de Russie,' vol. ii, p. 318, pi. xix, fig. 17 (1845), 

 the descriptions and figure agreeing very closely ; but not having seen the shell 

 it is difficult to speak certainly. This name is also prior to that proposed by 

 Captain Brown ; and should it be found that A. tenera of Eichwald is identical with 

 A. Wardi, then, if M. Teplofi be different in any way from A. tenera, it may be 

 necessary to substitute de Verneuil' s name for that of Captain Brown. Eichwald, 

 in ' Lethsea Rossica,' 1855-9, pp. 977 and 978, also gives a good description of the 

 shells M. Teplofi and M. tenera, and in almost identical language, so that each 

 description might well do for the other ; in addition both forms are said to come 

 from the same locality — the coal-measures of Lissitschanskaya county of the 

 Cossacks of the Don. It may be noted here that the form and comparative 

 dimensions of A Williamsoni are very variable. Mytilus Teplofi is said to occur 

 in the coal-mines of Lissitchia Balka (Donetz), below the limestone with Spirifer 

 mosquensis, but whether the bed is marine or no is not stated. 



Ludwig simply followed Eichwald with regard to Anodonta tenera, but more 

 correctly retained his first generic reference. 



I was able to examine the specimen to which Mr. Salter gave the name of 

 Anthracomya sanguinolaris in his palEeontological notes to the Survey Memoir on 

 the country around Bolton. It is preserved in the Museum of the Geological 

 Survey at Jenny n Street, and I have no doubt that this shell belongs to the 

 species under description. Another member of the genus Anthracomya occurs 

 near the same horizon, but in a different matrix. This one, however, I believe to 

 be A. Wardi. 



