﻿R. Etheridge, Jim. — Contributions to British Falceontology. 245 



1868, p. 204, fig. 44. Anthraeomya {Naiadites) Icsvis, Salter, Quart. Journ. Geol. 

 Soc, 1863, vol. xix. p. 79, fig. 2. Also Unio nueiformis, Hibbert, Trans. E,. Soc. 

 Edinb., 1836, vol. xiii. p. 245.) 



Sp. Chars. — Obliquely-broad-ovate, flattened, abruptly truncated 

 along the dorsal margin. Anterior end rounded ; posterior end pro- 

 duced ventrally, its margin obliquely rounded. Hinge-line not so 

 long as the shell, passing insensibly into the oblique posterior 

 margin. Umbones anterior, but not terminal, inconspicuous. Shell 

 marked with exceedingly close fine microscopic thread-like stria?, 

 with a few transverse wrinkles, which at times give it the ap- 

 pearance of being partially radiately striated. 



Obs. — A small shell was described by Dr. Dawson from the Coal- 

 measures of the South Joggings, Nova Scotia, under the name of 

 Naiadites loevis (= Anthraeomya, Salter), to which the present shell 

 bears so strong a resemblance that I was for some time quite at a 

 loss how to distinguish between them. However, A. Scotica is larger 

 than the Nova Scotian Naiadites Imvis. Judging from Dr. Dawson's 

 figure, the concentric striae are also more numerous, finer and closer ; 

 the posterior end appears to be more obliquely truncate, and the 

 beaks are more anterior. 



In pointing out the resemblance between these two forms, I am 

 supported by the opinion of Prof. T. Eupert Jones, F.R.S., who, 

 independently of any views of my own, suggested a reference of 

 the Scotch fossil to Dr. Dawson's species. It is sufiSciently distinct 

 from the other Anthracomyce and Naiadites described by Mr. Salter,^ 

 and Dr. Dawson, ^ not to reqiiire comparison ; but it appears to be 

 related to Anodonta ohstipa, Ludwig.^ Judging from figures only, 

 A. Scotica also resembles the shell figured by Prof. T. E. Jones 

 as the probable young of Anthraeomya Fhillipsii, Will.;* but the 

 concentric striae are much closer and the shell larger, as Prof. Jones's 

 figure is highly magnified. Dr. Hibbert long ago obtained, from 

 strata connected with the Burdiehouse Limestone, a shell to which 

 he gave the name of Unio nueiformis.^ Hibbert's figure represents 

 a shell in the uncrushed state of a particularly convex and globose 

 form. All our efforts to re-discover this shell have failed hitherto ; 

 and as Dr. Hibbert's collection was brought to the hammer, I am 

 afraid little chance remains of our ever being able to obtain access 

 to the type, although I have tried all means at my disposal. The 

 thought has often struck me whether this species might not be Unio 

 nueiformis in a perfectly flattened form, its usual condition. Al- 

 though some of the characters bear out this supposition, still, I 

 have seen no evidence in the flattened examples of A. Scotica of 

 the great inequality of the valves exhibited by Dr. Hibbert's figure. 



Loc. and Horizon. — The figured example is from the Linnhouse 

 Water between Calder Hall and Calder Wood, near Mid Calder, 



1 Iron Ores, Great Britain, pp. 230-1. 



2 Acadian Geology, 2nd ed., p. 204. 



3 '• J<>esh water fcjhells of the Coal-formation of the Urals," Falceontographica, 

 vol. X. t. 3, f. 2. 



•• Geol. Mag., Vol. VII. PI. IX., Fig. 18. 

 ^ Trans, E, Soc. Edinb,, vol. xiii. p. 245. 



