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. VVhiteaves 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, Scotland!) 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 ,J 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 arrano-ed 

 separately in the apparent laminae of the shell, as in Lingula, is not de- 



* PalEeozoic Foss., vol. i, yi. 114, tig-. 95. 



t See GeoL Mag,, 1877, p. 16, and Sil. Suppl., p. 202. 



X See Davidson Silur. Brach., pL ii. figs. 15-18 and 9-14. 



