430 Mr. R. Etheridge on Carboniferous Lamellibranchiata. 
posterior adductor-scars with satisfaction. Fig. 3 represents 
the posterior portion of a shell with a strong muscular scar, 
which, I think, may be that of J. crassa; it was obtained at 
Pitlessie with many fragments of that species, and from the 
same block of shale. The margin of the scar is strongly 
defined ; and there are several pits scattered along it and over 
the surface of the impression, probably marking the points of 
attachment of muscular fibres. 
In the water of Leith at Woodhall a bed of dark shale 
occurs, with a species of Myalina in abundance, the individuals 
varying in size from small specimens up to near that of the 
typical M. crassa. Except that the shell of the Woodhall 
form is thinner, and, as before stated, smaller, I cannot distin- 
guish one from the other. 
Localities &e. Cults Lime-works, near Pitlessie, Fife, “in a 
bed of shale over the Mountain Limestone ;” Fleming Collec- 
tion, Edinburgh Museum of Science and Art, and collection of 
the Geological Survey of Scotland : collected by Messrs. Bennie 
and Macconochie. Lugton Water, near Lugton Inn, near Dun- 
lop, Ayrshire, in shale in connexion with the lowest limestone 
of the Lower Carboniferous Limestone group; collection of 
the Geological Survey of Scotland, collected by Mr. A. Mac- 
conochie. Woodhall, water of Leith, in shale of the Wardie 
Shale series, Lower Carboniferous series; cabinet of Dr. 
Traquair, and collection of the Geological Survey of Scotland : 
collected by Mr. J. Bennie. Messrs. Armstrong and Young 
record MM. crassa from shale below the main limestone at 
Roughwood, and from clay-ironstone shale at Corrieburn*. 
In the article on “ Fife and Kinross,” in the ‘ New Statis- 
tical Account of Scotland’, is the following reference to the 
bed of shale at Cults Lime-works :—“ One of the beds of shale 
which overlies the main lime is composed entirely of shells of 
the genus Mytilus, the prevailing species being the M. crassus. 
These shells appear as fresh and entire as if they were still 
reposing on the mud bed of the primitive ocean in which they 
were produced. Not only are the external figure and internal 
structure preserved, but even the colour and original shelly 
matter seems to have sustained but little alteration.” 
Many of the valves of M. crassa from Cults have attached 
to them a large Spirorbis, described by Fleming in his 
memoir on the Testaceous Annelides as S. ambiguus. Mr. 
Bennie has met with a similar form at Roscobie, Fife. 
* Trans. Geol. Soc. Glasgow, 111. Supp. p. 52. 
+ Vol. v. p. 509. 
