454 R. ETHERIDGE, JUN., OX A LOWER-CARBONIFEROUS PRODUCTUS. 



50. On an Adherent Form of Productus and a Small Spiriferina 

 from the Lower Carboniferous Limestone Group of the East 

 of Scotland *. By E. Etheridg-e, Esq., Jun., F.G.S. (Read 

 June 21, 1876.) 



[Plates XXIV. & XXV.] 



I. On an Adherent Form of Productus. 



1. Introduction. — The habits and mode of life of the Producti 

 have been a fruitful source of speculation to the various authors 

 who have written on the genus. Some writers contended that the 

 various species lived a free and independent life ; others, on the 

 contrary, conceived that they were attached by muscular fibres 

 passing from the interior of the shell, and in fact acting the part of 

 a byssus, whilst yet others believed that their position during life 

 was at least aided by the long tubes or spines which usually orna- 

 ment their surface. 



I have now much pleasure in announcing the discovery (by Mr. 

 James Bennie, of the Geological Survey of Scotland) of an adherent 

 form of Productus, which, although not an entirely new fact in con- 

 nexion with this genus and its allies, has not, so far as I am aware, 

 been observed in so complete a manner before. Notwithstanding 

 that the facts now brought to light will not warrant us in applying 

 the principle to the whole of the Producti, they yet conclusively 

 prove that at least one form spent a very considerable portion if 

 not the whole of its existence adhering firmly by its spines to ex- 

 traneous bodies. 



The specimens were met with by Mr. Bennie in the Lower 

 Carboniferous Limestone group at two localities in East Lothian, at 

 one of which the form occurs rather abundantly, as the collections 

 of the Geological Survey of Scotland and Museum of Practical 

 Geology now collectively contain at least one hundred and forty 

 individuals. 



2. Bibliography. — Before proceeding to describe the specimens, it 

 will be as well to give a brief digest of the principal views held by 

 previous writers on the mode of life of Productus and the use of the 

 spines scattered over the valves of many of its species. 



1828. The Rev. Dr. Fleming considered it " probable that all the 

 Producti and Pentam-eri were free shells " f . 



1831. Baron von Buch, under the generic name of Leptcena, 

 described a shell resembling a Productus, with annulated tubes along 

 the hinge-line on each side of the umbo, and communicating by holes 

 placed under the hinge-line with the interior of the shell, and 



* Communicated with the permission of the Director-General of the Geolo- 

 gical Survey of the United Kingdom. 

 f British Animals, p. 380. 



