ANIMALS. 57 



SMotJieimii, and other fossils occurring at Tunstall Hill and Humbleton. A few 

 imperfect casts have occurred to me in the (? Rauchwacke) Limestone beds exposed at 

 low tide, opposite Hendon, near Sunderland : they may belong to a different species. 



Serpula (?) PUSiLLA, Geinitz. Tab. VI, figs. 7-9 ; Tab. XVIII, fig. 13 a, h, c, d} 



FoRAMiNiTES Serpuloides, (provisional), King. 1848. Catalogue, p. 6. 

 Sekpula PUSILLA, Gdnitz, 1848. Versteiner. Zechsteingebirg. und Rothliegend., p. 6, 

 tab. iii, figs. 3-6. 



INCH. 



Length, -^-^ 

 Breadth, -yL 

 Thickness, -^^ 



An oblong coil of sub-cylindrical, wire-like folds, white and granular. A central, 

 irregularly-twisted mass, of about ^ inch in diameter (see fig. 13 c), is inclosed in eight 

 or nine outer folds ; these are flat or slightly concave on their internal surface, and 

 convex externally, and are arranged longitudinally, not all on the same plane, but, 

 with the exception of the outermost folds, crossing each other at the extremities of the 

 coil at nearly right angles.^ The size of the folds gradually increases from within 

 outwards, but is subject to irregularities. 



This minute fossil appears to.be the cast of a tubular shell, there being more or 

 less space between each of the larger folds, which are in consequence rendered 

 extremely brittle. The shell, probably, was free and unattached. It sometimes occupies 

 an oblong, smooth cavity, which is not, however, excavated in any shell or foreign 

 substance, but appears to have been formed by the removal of the shell of the Annelid 

 after it was surrounded by the calcareous deposit. 



This little fossil appears to be identical with the species figured and described 

 by Geinitz (loc. cit.) as Serpula pusilla, from the Lower Zechstein of Corbusen, near 

 Ronneburg. 



It is of frequent occurrence in the Limestone at Humbleton. 



1 By Mr. T. Rupert Jones. 



2 The outer folds of this fossil bear some resemblance to those of the shells of some of the Agathistegia, 

 M. d'Orbigny's sixth Family of Foraminifera. The structure and arrangement, however, both of the inner 

 and the outer coils, present such important differences from the essential characters of the Foraminifera 

 referred to, that we can only be allowed this passing remark on the subject. 



