38 Prof. T. R. Jones and Mr. J. W. Kirkby on 



Pirnie Colliery, Leven, Fife, in parrot-coal, with fossils as 



before. 

 Methil, Fife, in blackband ironstone, with fossils as before. 



Carboniferous Limestone series : 

 Craigenglen, Campsie, Lanarkshire, in impure limestone, with 



C.fabulina and other fossils as before. 

 Crossgatehall, near Edinburgh, in ironstone nodules, with 



fossils as before. 



7. Cythere? (Carbonia?) bairdioides, n. sp. 

 (PL III. figs. 24, 25 ; 26 and 27 ?.) 



We have specimens of a form from Pirnie Colliery, Fife, 

 and Craigenglen, Campsie, which may ultimately prove to 

 belong to Carbonia. Only few examples of it, however, have 

 occurred, and its muscle-spot has not been seen ; so that for 

 the present we figure and notice it as a Cythere, with doubt. 

 Length y^ inch. 



It simulates a Bairdia in outline, having a regularly arched 

 dorsal border, with one end rather pointed, the other rounded, 

 and a very slightly convex ventral border. 



The Fifeshire specimens are much the largest, being TT inch 

 in length. A similar form, given to us by Mr. John Ward, 

 occurs in the Upper Coal-measures at Longton, Staffordshire. 



We have given particulars of the mode of occurrence and 

 associated fossils of the Entomostraca which we have just 

 described, with some detail, as such facts bear on the question 

 of the physical conditions under which they existed. It will 

 have been seen that the fossils usually found with most of the 

 species are the remains of Fishes, Amphibia (in a few instances), 

 Anlhracosia and shells of that family, the ubiquitous Spi- 

 rorbis carbonarius, and Plants (Ferns excepted). These are, 

 of course, the common fossils of the Paleeozoic coal-bearing 

 strata ; and about their natural habitats we do not know much 

 after all. In two localities species of Lingula * are associated 

 with them. In another (where Carbonia fabulina attains its 

 largest development) Leperditia scotoburdigalensis is abun- 

 dant ; and this Leperditia in other localities has sometimes 

 marine companions. One species, Carbonia subula, is com- 

 monly accompanied by Myalina modioliformis ?, Brown, 

 which is a very common fossil in the lower portion of the 

 Calciferous Sandstone series, and repeatedly occurs with 

 marine fossils, such as species of Axinus, Aviculopecten, 



* In the Trias of Germany Lingula is associated with Estheria of 

 brackish-water habitat. See ' Monogr. Fossil Estheria] Pal. Soc. 1863, 

 £P- 48, 49. 



