Palaeozoic B waived Entomostraca. 361 



1. Bollia hicolUna^ sp. nov. 

 (PL XII. l^gs. 14 a, h, c, 15, & 16.) 



r Fig. 14 : L. 23. H. 15. 

 Proportions : \ Fig. 15 : L. 22. H. 15. 

 (Fig. 16: L. 9. H. 7. 



Valves oblong, with rounded and nearly equal ends ; some 

 individuals proportionately longer than others ] straight on 

 the back, more or less outcurved on the ventral edge. The 

 surface is finely punctate, and bears two lobular elevations, 

 one on each side of a median bay-like sulcus, and constituting 

 two irregular obliquely transverse lobes, which converge 

 downwards and meet near the middle of the ventral region by 

 a low, narrow, bent isthmus, sinuous in the adult, but more 

 simply curved in the young state (fig. 16). The upper or 

 dorsal portions of this horseshoe lobe are swollen and project 

 outwards, and in the larger specimens somewhat divergently- 

 giving a symmetrically pinched and knobbly outline to the 

 dorsal profile of the carapace (fig. 14 h) . The ventral aspect 

 (fig. 14 c) shows the parallel, broad, lower margins conjoined, 

 and a slight median swelling at the curved neck or root of the 

 lobes on the sides ; there is also a slight indication of one 

 pair of the lobes more prominent on one side than the other. 



There are also two strong semilunar ridges, one at each end 

 of the valve, outside the lobes and parallel with the marginal 

 border, which has a slight outer rim. These two ridges die 

 out opposite each other, below the curved neck of the two 

 large lobes. 



In My. Vine's collection, nos. XLVilii_4, Lxii, LXiVi2, 13, all 

 from the " Build was Beds " of the Wenlock Sliale. 



A small or young form (fig. 16), with essentially the same 

 features as those of B. hicollina, occurs in Mr. J. Smith's 

 collection, no. 558, from Woolhope. 



2. Bollia unijlexa^ sp. nov. (PI. XII. figs. 17 a, h.) 

 Proportions :— L. 23. H. 16. Th. 10. 



Valves nearly semicircular, but somewhat modified by a 

 slope on the antero-ventral edge, where the narrow sharp ridge 

 just within the margin is much reduced in thickness. The 

 middle surface of each valve is raised into a strong somewhat 

 horseshoe-like or subcrescentric lobe, or rather into two broad, 

 suboval, unequal lobes, obliquely transverse to the length of 

 the valve, and united below. They converge rapidly down- 

 wards and join ventrally by a narrow sharply curved isthmus. 

 Towards the dorsal border they thicken and bulge out. A 



