54 



CARBONIFEROUS ENTOMOSTRACA. 



XII. POLYCOPE, G. 0. 8ars. 



PoLYCOPE, the only known type of the Polycopida (see p. 10), and belonging to the 

 distinct section Cladocopa (see p. 6), has a bivalved carapace, recognisable by its circular 

 or oval form, its obsolete sinus, and want of beak.^ 



In the Folycope the notch is obsolete or absent, a faint indentation or sinus in some 

 species indicating its place ; in others it is not at all marked. In this group the antero- 

 inferior region, if truncated, falls inwards or slopes obliquely downwards and backwards 

 from the greatest prominence in front. This corresponds to some extent with the shape 

 of those Cypridinads that have more beak than ventral keel, seeming to have a short chin, 

 in strong contradistinction to those which have the ''notch " high up, with or without a 

 deep sinus, and with more or less projecting antero-ventral quarters. 



1. POLTCOPE BuRROVii. Sp. uov. Plate II, figs. 2 a — c. 



Carapace equivalve (?), equilateral, subglobular, smooth. Side-view short-broad- 

 ovate, slightly smaller anteriorly. End-vieAV obovate, being broadest at the top. Edge- 

 view long-ovate, broadest in front. 



Muscle-spot obscurely visible. No indication of a notch or sinus. 



Length \ inch. Proportions — length 7 ; height 6 ; thickness 5. 



A few gregarious casts of P. Burrovii, some ferruginous, in grey Carboniferous 

 Limestone, have been collected at Settle, Yorkshire, by Mr. J. H. Burrow, M.A., after 

 whom the species is here named. 



2. PoLYCOPE SIMPLEX, /. and K. Plate II, figs. 1 a — c ; 10 ; 12. Plate V, figs. 1 a — d. 



Cypridinopsis simplex, J. ^ K., 1871. Trans. Geol. Soc. Glasgow, vol. iii, Suppl., 



p. 26. 



Carapace oval, compressed, smooth. A delicate marginal rim is seen on the ventral 



1 We do not know of any other fossil specimens besides these from the Carboniferous Limestone ; but 

 it appears to us possible that M. Barrande's Primitia soeialis from the Silurian of Bohemia (' Sil. Syst. 

 Bobeme,' vol. i, Suppl., p. 551, pi. 26, figs. 11 a — e), which is globose, about -Jgth of an inch long, with oval 

 outline and profile, circular end-view, and no notch, may be an ancient Polycope. 



