BRACHIOPODA. 
27 
the platform, reaching a height nearly equaling the depth of the valve. The 
platform itself is solid, except for a slight broad concavity on the posterior wall, 
which is continued into a minute conical excavation on either side of the base 
of the septum. No vascular markings are visible on any of the specimens. 
The external surface of the shell in Lingulasma Schucherti is beautifully 
sculptured. The concentric growth-lines are very fine, but at intervals bear 
bead-like granules, which thus become arranged in rows radiating from 
the apex of the valves. Over the cardinal slopes these granules become 
transversely elongated and crowded together, usually showing a tendency 
to merge into the growth-line on which they lie. We have no personal 
acquaintance with any species congeneric with Lingulasma Schucherti, but as 
suggested by Mr. Ulrich, the Lingula Canadensis, of Billings,* from an essen¬ 
tially equivalent fauna (Hudson group of Anticosti) as L. Schucherti, may 
prove to be a Lingulasma. Upon seeking to obtain specimens of the Anti¬ 
costi species, we have learned from Mr. White aves that Billings’ type-speci¬ 
men, and the only one in the possession of the Canadian Survey, was lost 
many years ago, and all endeavors to secure specimens from other sources have 
proved unsuccessful. As far as may be judged from the description and 
illustration of external features, given both by Mr. Billings and Mr. Davidson 
(the latter author has identified the species in the Llandeilo formation in Ayr¬ 
shire, Scotlandf) the agreement in size, proportions and surface ornamenta¬ 
tion is so close as to suggest almost a specific identity with the Illinois form; 
and, moreover, Billings’ figure indicates the presence of a prominent longitudi¬ 
nal septum. Mr. Ulrich directs attention to similar suggestive resemblances 
in the species Lingula granulata, Phillips, and L. tenuigranulata, McCoy,£ the 
former from the Llandeilo, the latter from the Bala beds. 
The shell substance in Lingulasma is calcareous, with a considerable 
intermixture of organic matter. Whether these components are arranged 
separately in the apparent laminae of the shell, as in Lingula, is not de- 
* Palaeozoic Foss., vol. i, p. 114, fig. 95. 
t See Geol. Mag,, 1877, p. 16, and Sil. Suppl., p. 202. 
I See Davidson Silur. Brach., pi. ii. figs. 15-18 and 9-14. 
