Notes on Palceozoic Entomostraca. 343 



10. Fig. 1 is the ordinary variety of Beyricliia Kloedeni, M'Coy ; 

 such as is shown in the " Mem. Geol. Surv," vol. ii. part i. 

 pi. 8, figs. 17 and 18 ; and "Ann. Nat. Hist." series 2, vol. xvi. 

 pi. 6, fig. 7. Eight valve. Length -^ inch. 



10*. Fig. 2 seems to be a right valve of B. Kloedeni, shortened 

 by pressure. Length -^ inch. 

 In the "Zeitsch. d. d. geol. Ges." xv. p. 671, pi. 19, figs. 7-11, 

 and vol. xvii. p. 364, pi. 10, fig. 6, M. Eichter has described and 

 figured BeyrtcJiia Kloedeni as plentiful in the Upper-Silurian con- 

 glomerate and Nereiten-Scbiefer of Thuringia. This appears to me 

 to be B. Kloedeni, var. torosa (A. N. H. 2, xvi. p. 167, pi. 6, fig. 11). 



11. Fig. 3 is £. Wilchensiana, Jones (op. cit. p. 89, pi. 5, figs. 18-20). 

 Eight valve. Length 4^ inch. 



12. Fig. 4 is an obscure cast of the right valve of a Beyricliia closely 

 allied, apparently, to B. affinis, Jones (op. cit. p. 170, pi. 6, fig. 16). 

 Length -4% inch. 



13. Fig. 5 is a cast of a right valve, having an approximate re- 

 semblance to B. intermedia, J. and H. (Ann. N. H. ser. 4, vol. iii. 

 p. 218, pi. 15, fig. 7; and vol. xv. p. 55, pi. 6, fig. 11), from 

 the Upper Silurian of England and the Carboniferous of Eussia. 

 Length -^ inch. 



11*. Fig. 6 appears to be a large B. WilcTcensiana (left valve), 

 obliquely squeezed. Length -^ inch. 



14. Betrichia Hollii, sp. nov. Plate X. Fig. 7. 

 Length, ^ inch. 



This Beyricliia, represented by a small cast (in pyrites) of the 

 inside of a left valve, has very much of the aspect of B. intermedia, 

 J. and H., mentioned above, but it is less truly semicircular, being 

 contracted towards one end (anterior) ; it has a broader marginal 

 rim ; the valleys dividing the lobes, though confined to the dorsal 

 region, are less symmetrical ; and the prominent lobe does not 

 appear to be the central, but the posterior lobe. In this last point, 

 however, there is some obscurity, on account of the valve having 

 been somewhat crushed at the posterior third. These differences 

 demand a nominal separation of this from the allied species, and I 

 name it after its discoverer, Dr. H. B. Holl, F.G.S., who on this and 

 other occasions has kindly co-operated with me in working out the 

 Paleeozoic Bivalved Entomostraca. 



Dr. Holl discovered this unique specimen in Meneevian flags from 

 St. Davids, in 1866. It was associated with Protospongia fenestrata,^ 

 Salter, and therefore belongs probably to the horizon of Paradoxides 

 Davidis, rather above the Middle Meneevian flags of Dr. Hicks's 

 classification. 



In the far-remote Menaevian Period there were Bivalved Ento- 

 mostraca, small, but of much interest, especially as being the oldest 

 that we yet know. 



1. Entomiclella bujjrestis {Salter). " Lower and Middle Mena3vian," A. N. H. ser. 

 4, vol. xi. p. 417. 



1 C^art. Journ. Geol. Soc. vol. xx. p. 238, and xxvii. p. 401. 



