4 



POLYCOPE. 55 



edge of some valves. The curvature of outline and the amount of gibbosity are variable. 

 Side-view oval (sometimes ovate by increased ventral convexity) ; obliquely truncate at 

 the antero-ventral region, and hence a slight angular anterior prominence. End-view 

 narrow-obovate. Edge-view narrow-acute-oval. 



A faint trace of the Muscle-spot occurs on some specimens. 



No indication appears of a notch at or under the projecting angle. In this feature our 

 little fossil resembles the very small existing PoJycope orbicularis, Brady (' Trans. Lin. 

 Soc.,' vol xxvii, p. 471, pi. 35, figs. 53 — 57), which, however, is rounder and thicker, 

 has an irregular reticulate ornament, and is indented with the very shallow and nearly 

 obsolete sinus rather higher up on the front. 



The fossil specimens (in a nodule) from Braidwood, Lanarkshire, show a neat reticu- 

 late structure of oblong meshes and scattered superficial pits. One small specimen is 

 very much more ovate than the others, but this may be a character of age or of sex. 

 Carluke (Plate 11, fig.l). Length yg- inch. Proportions — Length 10 j height 1 ; thickness 5. 

 Meath (fig. 12) . . „ | „ „ „ 9; „ 6. 



Cork (fig, 10) . , „ i „ „ „ 10; „ 7. 



Poll/cope simplex is not rare. We have it from the Carboniferous Limestone of Little 

 Island, Cork (IMr, Joseph Wright, F,G,S,) ; from Duleek, Co, Meath (a cast^ in the 

 Museum of the Geological Survey of Ireland) ; and a large specimen from limestone of 

 the same age at Limerick. Probably of the same species, but not well exposed, are some 

 imbedded specimens in the same limestone from the Isle of Man (Mr, E, W. Binney, 

 E,R.S.). 



A nodule of ironstone from Braidwood, near Carluke, Scotland, contained seventeen 

 specim.ens (including impressions) of P. simplex, having brownish-grey shells, smooths 

 translucent, showing reticulate structure, and with a neat little ventral rim to some of the 

 valves (Dr. Rankin's collection). We also refer to this species two small, smooth, com- 

 pressed casts" from the Hosie Limestone series, South Hill, Campsie, near Glasgow, 660 

 fathoms below the Ell Coal (Mr, J. Young'). 



Figs. 1 a — c. — Shell ; magnified eight diameters ; from Braidwood, Carluke, 



Pig. 10. — A smooth grey shell; Cork, 



Eig. 12. — A cast in limestone ; Duleek, Meath, Ireland (Geol, Surv. Map, Sheet -^), 

 This specimen from Duleek is one of some gregarious casts in a light-grey Carboni- 

 ferous Limestone, and is restored in the figure from a wax impression. It shows obscurely 



' Referred to as " Cypridina primceva^^ in the 'Annals Nat. Hist.,' ser. 3, vol. xviii, p. 48, 



2 These were associated with " Cypridina primceva" in the ' Glasgow List' of 1871, p. 27. 



3 Mr, Young informs me that " this Polycope is found, with many marine shells, in dark-grey shale, 

 lying upon the Hosie Limestone at Campsie and Kilbride, The beds are in the 'Lower Limestone series.' 

 Craigenglen, which has yielded a great many species of the smaller Entomostraca, is on the same South 

 Hill of Campsie. The beds lie under the 'Main Limestone,' and are therefore lower in position than the 

 Hosie Limestone, which is 22 fathoms above the Main Limestone." 



