CARBONICOLA ROBUSTA. AT 
near Ayr, Dalmellington, Airdrie, Cummock and Shotts, and above the Drumgray 
Coal of Lanarkshire. England: Lower yard seam, Fulledge Colliery, Burnley. 
Above the Arley Mine, Lancashire. Middle Coal-measures, Pendleton, Lancashire. 
Lofthouse and Killingback-beds, near Leeds. Roof of Shale Coal, Wakefield. 
Brockwell Seam, Wylam, Northumberland. Above the Holly Lane and Bowling 
Alley, and 10-foot Seams. Shale above 4-foot Coal, Wetley Moor. Shale above 
Woodhead Coal, Froghall, all in the Lower Coal-measures of North Staffordshire. 
Coalbrookdale (Pennystone Beds). Alfreton, Tibshelf (small form), and Codnor 
Park, Derbyshire. 
Observations.—Through the kindness of Prof. Prestwich I have been able to 
study and figure the original type-specimen, PI. I, figs. 2, 2a, which apparently 
differs widely from Salter’s type ; but it was pointed out to me by Mr. H. Bolton, of 
the Manchester Museum, Owens College, that Prof. Prestwich’s shell was crushed 
and incomplete, as was, indeed, shown in the original drawing, the lines of growth 
terminating abruptly without becoming reflected upwards to the superior border. 
A smaller form, Pl. II, fig. 3, kindly lent me by Dr. John Young, of Glasgow, 
approaches somewhat to the original figure, its posterior end not being developed. 
This I believe to be a young state of the shell, from the fact that a series of inter- 
mediate specimens can be shown. PI. I, fig. 6, from the Braidwood Collection of 
Dr. Hunter, and PI. I, fig. 3, another of Dr. J. Young’s specimens, are such forms. 
De Koninck’s figure of this shell (‘ Les Animaux Fossiles de la Belge,’ pl. u, 
fig. 1) is hke Dr. John Young’s small specimen ; but this species seems to be rare 
in the coal-fields of the Continent, as no other author, except perhaps Achepol 
(‘ Niederrh.-Westf. Steinkohlen-Gebirge, Atlas,’ Suppl. 1, figs. 19, 20, A. crassa ; 
and Suppl. 3, A. caudata), records its presence; and, except at Brussels, I have 
seen none in any museum abroad. M‘Coy (‘ British Paleozoic Fossils,’ p. 515), 
judging from Sowerby’s figures of Unio subconstrictus (‘ Min. Conch.,’ Tab. xxxiii, 
figs. 1—3; and U. robustus, ‘ Trans. Geol. Soc.,’ ser. 2, vol. v, pl. xxxix, fig. 14), 
considered that the latter was only an adult form of the former, the figure of 
U. robustus appearing shorter and deeper than natural from the oblique fracture of 
the posterior end. 
I have not seen very many hinge-plates of C. robusta ; but, judging from those 
I have seen, this species seems to have possessed a more constant form than 
others. Mr. Salter figures a hinge-plate in the Appendix to the ‘ Geological 
Survey Memoir, the Country round Wigan,’ which agrees very closely with 
Pl. I, fig. 9. In young forms the anterior part of the hinge-plate does not seem 
to be developed into a cardinal tooth to the extent which obtains in older 
specimens. In Salter’s figure there is a little irregularity shown in the hinge- 
plate towards the posterior end: I have seen a similar condition in some of the 
interiors of other species of Carbonicola, and consider it to be the position of the 
