President's Address. 365 



To the genus Bitrupa, Berkeley, he adds a new species, and 

 figures Ortonia carlonaria and an undetermined species of 

 Vermilia. 



BEACHIOPODA. 



The most important publication dealing with Scottish 

 Brachiopoda is the late T. Davidson's Supplement to his 

 great monograph, published in 1884, which deals with a 

 great amount of material from the Scottish Silurian rocks, 

 especially from the Gray collection and that of the Geo- 

 logical Survey.^ In his presidential address to this Society 

 in 1881, Mr Etheridge estimates the then known spefties of 

 Brachiopods from Scottish Silurian rocks at 53.^ Mrs Gray's 

 list, published in the Appendix to volume i. of the Memoirs 

 of the Geological Survey of the United Kingdom, enumerates 

 120 species from the Girvan region alone.^ The list given 

 in the same volume by the Geological Survey from the whole 

 of Scotland amounts to 140 species.^ These great additions 

 to Etheridge's lists are mainly due to the fact that most of 

 the Silurian Brachiopods in the collection of the Geological 

 Survey of Scotland had been examined by Mr T. Davidson 

 during his later years. An interesting point in the work of 

 the Geological Survey, is the finding of species of Paterina 

 and Obolella in the Cambrian and Arenig rocks of the north- 

 west Highlands and Lanarkshire. All recent Brachiopods pass 

 through the stage of Paterina, and some through an Obolella 

 stage, during development, and it is a suggestive fact that 

 adult forms with these embryonic characters should be found 

 in the oldest rocks from which Brachiopod remains have as 

 yet been dug up. 



LAMELLIBEANCHIATA. 



The decade prior to 1880 was one of great activity in the 

 description and classification of Scottish Palaeozoic Lamelli- 

 branchs, chiefly owing to the energy of Eobert Etheridge, 



1 "Mod. Brit. Foss. Brach,," Palceontogr. Soc, vol. v., 1882-1884. 



2 Proc. Boy. Phys. Soc. Edin., vol. vii. p. 27, 1881, 



* Mem. Oeol. Sur., "The Silurian Rocks of Britain," vol. i. pp. 686-697, 

 1900. 

 ilbid., pp. 675-679. 



