566 T, R. JONES AND J. W. KIRKBY ON 
intermediate beds, though Z. scotoburdigalensis continues on in the 
shales and ironstones, where Plant- and Fish-remains come in as 
common fossils. We may here mention that six or seven species of 
the Ostracodous genus Carbonia *, with varieties, appear to have been 
constant inhabitants of the freshwater or brackish lagoons and shal- 
low shore-waters where the British Coal-measures were formed ; and 
they have not been found in any marine stratum of the Carboni- 
ferous series. 
The Bairdice which we have to describe in this paper include all 
that are known from British Carboniferous strata. They are from the 
Upper and Lower divisions of the Carboniferous-Limestone series and 
the Calciferous-Sandstone series of Scotland, from the Yoredale Rocks 
and Scar Limestone of the Northern Counties of England, and from 
the Carboniferous Limestone of Wales and the West of England. 
The lowest portion of the series where they have been seen is 
probably the Calciferous Sandstone of Fife, where B. plebeia, B. 
nitida, and B. siliquoides are found from 3000 to 3800 feet below the 
base of the Carboniferous-Limestone series. The highest position in 
which Carboniferous Bairdie have been found in Scotland is in the 
upper division of the Carboniferous Limestone ; and in England they 
occur in a somewhat equivalent position in the upper beds of the 
Yoredale Rocks. Though we have no specimens from the Millstone- 
grit or the Coal-measures, it is evident that several of the species. 
continued to exist, in other areas, during the deposition of these 
Upper Carboniferous strata, for they reappear in abundance in the 
Permian rocks of Durham and Yorkshire and of Germany. 
It should be mentioned that we are largely indebted to Mr. John 
Young, of Glasgow, for specimens and for information as to dis- 
tribution ; also to Messrs. James Thomson, James Armstrong, and 
David Robertson, of the same city; to Mr. J. R. J. Hunter, of 
Braidwood ; to Mr. R. Etheridge, Jun., formerly of the Geological 
Survey of Scotland, now of the British Museum; to Mr. Charles 
Moore, of Bath, Dr. H. B. Holl, and others. Our examination of 
hundreds of specimens belonging to the Geological Survey of Scot- 
land has greatly enlarged our knowledge of these Kntomostraca. 
Barrpra, M‘Coy. 
Professor M‘Coy briefly.described the genus as :—“ Shell elongate, 
fusiform, suddenly tapering at both ends ; avery short proportion of 
the valve overlaps the abdominal margin.” 
The generic characters have been more fully noticed by one of us 
in a ‘ Monograph of the Entomostraca of the Cretaceous Forma- 
tion,’ 1849, p. 22, and in a paper on “ Permian Entomostraca 
from Durham,” ‘Trans. Tyneside Field-Club,’ vol. iv. 1859, p. 189. 
More recently Prof. G. 8. Brady has given an account of the genus, 
from a study of the recent species, in the ‘Transactions of the 
Linnean Society,’ vol. xxvi. p. 388, and the ‘Transactions of the 
Zoological Society,’ vol. x. p. 383. 
* See Ann. & Mag. Nat. Hist. ser. 5, vol. iii. p. 28, pls, ii. & iii. 
