ANTHRACOMYA MINIMA; Var. ELS 
13*, ANTHRACOMYA MINIMA, var. cARINATA. Plate XVI, figs. 35—39. 
Non AnrHracomya carrnata (pars), Hind. Quart. Journ. Geol. Soc., vol. xlix, 1893, 
p- 273, pl. x, figs. 16, 16 a. 
General Characters.—Very much produced transversely, anterior end very 
small and almost obsolete, bluntly rounded, sloping rapidly into the inferior border, 
which is so slightly convex as to appear almost straight. The posterior part is 
produced, forming about seven-eighths of the shell, with a strong oblique ridge 
passing downwards and backwards to the inferior border at the junction of the 
third and posterior fourth of its extent, when it becomes lost on the surface of the 
shell. Anterior to the ridge the shell is sinuated and flattened, and very rapidly 
compressed into the lower border. Above the ridge the shell is also rapidly 
compressed into the superior border. The posterior border is curved elliptically. 
The hinge-line is straight, equalling about three-fourths of the length of 
the shell in measurement. The umbones are situated very anteriorly, tumid, 
and small. 
The exterior is covered with fine striz and lines of growth, which, starting 
from the anterior end, become curved upwards as they reach the oblique swelling, 
and are reflected up to the superior border. Periostracum thick and wrinkled. 
Interior not seen. 
Dimensions.—Fig. 39, Pl. XVI, measures— 

Antero-posteriorly : ; . 22mm 
Dorso-ventrally (at See mia) : 3 Oo nami: 
Laterally  . . a) 64 mam; 
Localities —From an ironstone band on the Middle Coal-measures of Lancashire 
at Prestolee. The Knowles Ironstone bands, North Staffordshire Coal-field. 
Remarks.—The specimen I first described I now find to have greater affinity 
with A. pumila, Salter ; and, moreover, it comes from the locality of Salter’s type. 
I had neither seen the series of shells from the South Wales Coal-field in the 
Cardiff Museum, nor the intermediate forms which connect A. carinata with 
A. minima. I have now found them in the beds both in Lancashire and North 
Staffordshire which contain this shell, but owing to the differences in form and 
size, and the comparative rarity of this variety, I have still retained the name 
carinata, but as a varietal form of A. minima. The chief difference which marks 
off this variety is in the very rapid and excessive growth of the posterior end, and 
the consequent throwing into greater relief the oblique ridge, which, instead of 
being directed towards the inferior posterior angle, is left behind some distance 
along the lower border. 
