VINE : CAEBONIFEROUS ENTOMOSTEACA, ETC. 233 
4. Baikdia plebeia, Reuss. (PI. XII., Figs. 3, 5, 5a.) 
^«iVc/ia />Ze6eia, Reuss, 1854, Jahresbericht weltterau Gesellsch, 1854, 
p. 67, Fig. 5. 
Bairdia plebeia, Kirkby, Ann. Mag. Nat. Hist. Ser. 3, vol. II., p. 324, 
Figs. 1 & 7. 
Bairdia plebeia, Jones & Kirkby, Quart. Jour. Geol. Soc, Not. 1879. 
In the last paper, several synonyms and special details are given. 
The Yorkshire specimens of this form differ somewhat from 
the variations of the type furnished by Jones & Kirkby, in their 
most recent paper of the genus Bairdia, from the Carboniferous rocks 
of Britain. One of the specimens, in the pointing of the pos- 
terior extremity, makes a very near approach to some of my Scotch 
and Northumberland specimens of B. suhmucroiiata J. & K., but I 
think that the whole of the specimens figured, may be placed under 
B. ])lebeia, Reuss. 
Formations : Permian and Carboniferous. 
Localities: Hurst, Richmond; Messrs. Jones & Kirkby give 
Weardale, Durham ; Wyebourne, Cumberland, and Settle, Yorkshire, 
as northern English localities ; and they say that B. plebeia appears 
to have been the prevailing form of the genus during the upper Palaeo- 
zoic periods." A large number of other localities are given by 
authors, both in Scotland, and a few in Wales. It is not very 
common, so far as I can judge, in the North Yorkshire shales. 
5. Baikdia brevis. Jones & Kirkby (PI. XIL, Figs. 4a, 4a.)? 
B. brevis, J. & K, 1867, Trans. Geo. Soc, Glasgow, vol. H., p. 221. 
B. brevis, J. & K., 1871, Armstrong & Young's Cat. Carb. Foss. of West 
Scotland. 
B. brevis, J. & K., Quart. Jour. Geo. Soc., November 1879, p. 575, pi. XXXI., 
Fig. 1 & 8. 
In the last of these three papers, the authors' describe and 
figure, with its several variations, this delicate little species, " which, 
compared with its height, is the shortest species of the genus," 
known to them. 
Localities : Hurst. The other English localities given by the 
authors, are Wyebourne, Cumberland ; Weardale, Durham ; Charter- 
house, Somerset ; and Scremerston, near Berwick-on- Tweed. 
Family II. — CYTHERID^. 
Genus CYTHERE, MuUer. 
*' Carapace closed, resembling a diminutive peach stone ; valves 
