132 I'UOCEEDINGS OF THE MALACOnOGICAl/ SOCIETV. 



paper will now be referred to under the particular shell with which 

 they are associated, some of the material being in the collection of the 

 British Museum, which includes the ' Morris ' specimens described 

 in 1851. 



Family MYTILID^. 



VoLSELLA. MODIOLUS (Linnasus). 



Mytilus modiolus, Linnaeus : Syst. Nat., 1758, 10th ed., p. 706. 

 David Robertson: Trans. Geol. Soc. Glasgow, 1883, vol. vii, pt. i, 

 p. 31. 



The Geological Department of the British Museum possesses 

 several small isolated pearl bodies which were presented by David 

 Kobertson, Esq., in 1883, who collected them in the marine Post- 

 Pliocene deposits of the Clyde Basin at Garvel Park. Some of these 

 attain a diameter of 3 millimetres, whereas others are very much 

 smaller. Externally they present a shiny nacreous appearance, their 

 inner structures being composed of concentric layers in combination 

 with the usual radial structure. Similar specimens are listed by 

 Mr. Robertson in his paper "On the Post-Tertiary Beds of Garvel 

 Park " as belonging to Mytilus modiolus of Linnaeus, a specific deter- 

 mination which is here retained, although placed under Scopoli's 

 genus Volsella, that having priority of Lamarck's Modiola, with which 

 the species is usually associated. 



Geological age. — Post-Pliocene (marine glacial beds). 



Locality. — Garvel Park, Clyde Basin, Scotland. 



Collection. — British Museum (D. Robertson Coll.) [L. 980]. 



Family AVICULID^. 

 Inoceramus Goldfussianus, Orbigny. PI. IV, Fig. 1. 



Inoceramus Cripsii, Gold! uss (non Mantell) : Petrefacta Germaniae, 



1836, vol. ii, p. 116, pi. cxii, fig. Ad. 

 Inoceramus Goldfussianus, Orbigny : Paleontologie Fran9aise, Terr. 



Cretaces, Lamellibranchia, 1845, p. 517, pi. 411; Prodrome 



Pal. Strat., 1850, vol. ii, p. 250. 

 The specimen figured by Goldfuss is a convex natural cast repre- 

 senting the interior of a left valve, studded with numerous small 

 pittings, which are generally of uniform size. A patch of the original 

 shell is still preserved, showing the nearly equidistant concentric ridges 

 with their fine lineations, which extend as well over the surface of the 

 sulcations. The pittings are of fairly regular arrangement, and follow 

 the concentric character of the sculpture, appearing to be absent on 

 the umbonal surface of the valve and on the region immediately below 

 the dorsal line. As pointed out originally by Goldfuss, they represent 

 cavities for the reception of wart-like prominences that would be 

 present on the internal surface of the valve. No mention is made, 

 however, of the fact that such tubercles would indicate pearl-growths, 

 although there is no doubt that this is their true interpretation. The 

 illustration published by Goldfuss forms probably the earliest known 

 figure of a fossil shell showing the remains of pearl-structures. It has 



