ANTHRACOMYA WILLIAMSON! 99 



antero-posteriorly, its greatest dorso-ventral measurement (towards the posterior 

 end) is 32 mm., and 22 mm. from side to side : this specimen is more typical in 

 shape than the one figured. I noted also in the Museum at Brussels a large 

 example measuring 54 mm. from before backwards, from the Coal-measures of 

 Lougchamps, but have not met with the form in other Continental museums. 



4. Anthracomya Williamsoni (Brown). Plate XIV, figs. 12—31 ; Plate XV, fig. 10. 



? Anodonta teneea, Ekhivald. Urwelt Eusslands, p. 101, pi. iv, figs. 2, 3, and 4, 1840. 

 ? Mttilus (Modiola) Teplofi, de Verneuil. Geol. de la Eussie, vol. ii, p. 318, 



pi. xix, fig. 17, 1845. 

 — pe^epes, de Ryckholt. Melanges Paleontologiques, p. 158, le part, 



pi. viii, figs. 1, 2, 1848. 

 Modiola Williamsoni, Broivn. Fossil Conchology, pi. lxxi, figs. 24, 25, p. 172, 



1849. 

 Modiolopsis teneea, Eichwald. Lethaea Bossica, p. 977, pi. xxxix, fig. 4, 1855-9. 



— Teplofi, Eichwald. Ibid., p. 978, 1855-9. 



Antheacomta sanguinolabis, Salter. Memoirs of the Geological Survey of 



Great Britain, " The Geology of the 

 Country around Bolton-le-Moors," 

 p. 35 (no description or figure), 1862. 



Anodonta teneea, Ludwig. Pal. Urals; Paheontographica, vol. x, p. 20, pi. iii, 



fig. 13, 1863. 



Antueacosia Weissiana, Geinitz. N. Jahrbuch fiir Mineralogie, &c, 1867, p. 682. 



Pleueophobus subcostatus, Meek and Worthen. Geol. Surv. Illinois, vol. ii, 



p. 347, pi. xxvii, figs. 2, 2 a, 1866. 



Antheacosia Bilboensis, Kinahan. Geol. of Ireland, pi. iv, fig. 5, 1878. 



— — Baily. Geol. Surv. Ireland, Exp. of Sheet 137, p. 12, 1859. 



— Haezi, Achepol. Niederrheinisch-Westfalische Steinkohlen-Gebirge, 



Atlas, p. 109, Supplement ii, figs. 8 and 9, 

 1880—1883. 

 Antheacomta elongata, Hind. Quart. Journ. Geol. Soc, vol. xlix, p. 266, pi. x, 



figs. 1—12, 1893. 



Specific Characters. — Shell very transversely elongate, very inequilateral, wedge- 

 shaped, and compressed. The anterior end is small, narrow from side to side and 

 above downwards, with an acutely rounded border, which passes downward 

 rapidly into the inferior border, and forms above a blunted right angle with the 

 hinge-line. The posterior end is expanded and produced, and is gradually 

 compressed into its borders, but much more rapidly so upwards into the 

 hinge-line. The inferior border is nearly straight, but is slightly sinuated about 

 its centre. The posterior border is truncate, with the upper and lower angles 

 more or less rounded. The hinge-line is straight, raised, and compressed 



