114 CARBONICOLA, ANTHRACOMYA, AND NAIADITES. 



Dimensions. — Fig. 46, PI. XVI, measures — 



Antero-posteriorly . . . .8 mm. 



Dorso-ventrally (behind) . . .5 mm. 



From side to side . . . . 4 mm. 



Locality. — Dalmeny railway-cutting, near Wester, Dalmeny. Lower Carbo- 

 niferous of Scotland. 



Observations. — This little species has the characteristic shape of the genus. 

 A set of fourteen specimens are in the Geological Survey Collection of Edinburgh, 

 labelled A. Valenciensis, MS., R. Etheridge, jun., all from the locality stated 

 above. This species appears to be the smallest and, at the same time, the 

 earliest member of the genus known in Carboniferous times. I know of no other 

 species which can be mistaken for it, as it is much more regularly globular than 

 A. minima, unless it turns out to be the perfect form of A. laevis, var. Scotica, which 

 is only known in a much-compressed condition. 



12. Anthracomya folchl'A, sp. nov., Hind. Plate XV, figs. 29 — 49. 



Antheacomya pumila, pars, Hind. Quart. Journ. Geol. Soc, vol. xlix, 1893, 



p. 269, pi. x, figs. 28 and 29. 



Specific Characters. — Shell transversely oblong, convex, at times almost 

 cylindrical. The anterior end is compressed, and has its border almost circularly 

 curved, the posterior superior angle not being prominent. The upper border of 

 the anterior end is much below the level of the umbones. The inferior border is 

 straight or slightly concave, joining the anterior border by an abrupt curve, 

 while posteriorly it forms a more or less obtuse angle with the obliquely truncate 

 posterior border, so that the posterior inferior angle is well marked and somewhat 

 acute, and this point is the most posterior portion of the shell The hinge-line is 

 straight, deviating very slightly from parallelism with the ventral edge. The 

 umbones are obtuse, gibbose, almost contiguous, and raised above the hinge-line. 

 They are situated anteriorly at a point distant from the anterior end equal to about 

 one-fifth the length of tin; hinge-line. The umbones are excavated in front by a 

 well-marked lunule, and posteriorly there is a well-marked escutcheon or groove 

 on each side of the external ligament, which is erect, and small and short. The 

 posterior or greater portion of the shell is convexly swollen in an oblique direction 

 from the umbo to the posterior inferior angle. The compression anterior to the 

 ridge, characteristic of this genus, is only seen at the lower edge of tin 1 shell, about 

 the centre, as an almost obsolete broad sulcus. Above the swelling the shell is 



