16 
T. Davidson — On New Scottish Brachiopoda. 
The muscular impressions in Obolus are more spread out than in 
either Discina or Siphonotreta, and Prof. King thinks that tliis difference 
appears to be explained thus : tke latero-cardinal scars in Siphonotrela 
are more crowded together than they are in Obolus, and the central 
projecting portion of the undercut ‘ spectacle ’-like impressions in 
Obolus advance more to the anterior margin of the valve than the 
corresponding impressions in Siphonotreta. 
2. Lingula Canadensis, Billings (?). PL II. Figs. 4. 4a. b . 
Lingula Canadensis, Billings, Geological Survey of Canada, Fossils, 
vol. i. p. 114, fig. 95, June, 1862. 
Of this large and beautiful Lingula Mrs. Gray has found one in- 
complete example. It was obtained from the Breccia-conglomerate 
of Balcletchie, near Girvan, in Ayrshire. This conglomerate rests 
upon the rock at Balcletchie, which some geologists have considered 
to be of Llandeilo age. 
It is not possible to describe the complete shape of the fossil, 
because the two anterior thirds of its valves are alone preserved. It 
however, so nearly agrees in size, shape, and sculpture with the 
fossil described and figured by Billings from the Hudson Kiver 
group of Anticosti, that we have thought it preferable to leave it 
provisionally under that designation. 
It is of a quadrate or sub-pentagonal elongated shape, posteriorly 
obtusely acuminated, broadest anteriorly; the sides are almost 
straight, front very slightly convex with broadly rounded angles. 
The smaller valve is much flattened anteriorly, and but slightly 
convex posteriorly or towards the beak. The larger valve is very 
much more convex. The surface of both valves is covered with fine 
bead-like longitudinal radiating ridges, with shorter and narrower 
ones occasionally intervening between each larger pair, and especially 
so in the proximity of the front and lateral margins. From five to 
eight of these ridges occupy the breadth of a line. The interspaces 
between the longitudinal ridges are about three times the width of 
each ridge, and from eack of the bead-like projections, are horizontal 
or concentric much narrower rounded ridges with interspaces of 
about equal breadth ; as seen in the enlarged drawing, Fig. 46. of 
our Plate. 
The two perpendicular and horizontal ridges producing on the 
surface of the valves a beautifully reticulated sculpture, to which 
the rows of bead-like projections give additional prominen ce. 
In size, Mrs. Gray’s specimen, when complete, cannot have 
measured much less than one inch and nine lines in length, by one 
inch and three lines in breadth. These proportions recall those of 
L. tenuigranulata, M'Coy, a closely allied species, and which would 
differ from the one under description by its much more finely and 
closely reticulated sculpture. 
3. Lingula quadrata, Eichwald. PL II. Figs. 2, 3. 
Crania quadrata, Eichwald, Zool. Specialis, vol. i. p. 273, pl. 4, fig. 2. 
1829. 
Lingula quadrata, De Verneuil, Geol. of Bussia, vol. 2, pl. i. fig. 10. 
1845. 
