Muscle Systems of some Inarticulate Brachiopods

The muscle systems of Lingula, Discinisca, and Crania have been described in considerable detail and in general with progressive accuracy by numerous workers since the time of Cuvier and Owen, and the best and apparently most recent accounts are to be found in two works by Blochmann (1892, 1900). But I am not aware that there exist any diagrams of these systems readily accessible to the palaeontologist; Fischer and Oehlert (1887) give some figures adapted from Joubin (1886), but these are in some respects inaccurate and Blochmann's work, other than on Crania, has not apparently found its way into palaeontological literature. The purpose of the present note is little more than to provide diagrams of the shell muscles of the above-mentioned living genera, and to attempt certain palaeontological restorations. I have had the opportunity of verifying the structures in spirit Lingula and to some extent in Crania, thanks to the kindness of Dr. C. F. A. Pantin.

VI.—On the Muscular Impressions of Cœlonautiluscariniferus J. de C. Sowerby, sp., compared with those of the Recent Nautilus

In examining the remarkably fine series of examples of Cœlonautilus cariniferus, mostly from the Carboniferous Limestone of Ireland, contained in the Geological Collections of the British Museum (Nat. Hist.), some were found to exhibit upon the cast of the body-chamber distinct marks of the shell-muscles. In one specimen (No. 50190) these are so perfect as to give a very clear outline of their form, and some of the test having been removed, their entire course can be made out.