Palceozoic Bivalved Entomostraca. 357 



vexity of the valve, and lies closely against one of the main 

 lobes, which are quite confluent below. The surface of the 

 valves is delicately reticulate, the marginal rim is distinct and 

 uniform. The edge view is sharp-ovate^ notched at the sides 

 not quite symmetrically. 



This rare form (no. 29 of Mr. J. Smith's collection) is 

 from Dormington, near Stoke-Edith. It is apparently related 

 to the subvariety clmisa (fig. 9), but its reticulate ornament 

 and other features sufficiently distinguish it. 



4. Beyrichia Maccoyiana^ Jones. 

 (PI. XII. figs. 11 a, 6, c, 12, laa, I.) 



Beyrichia Maccoyiana, Jones, Ann. & Mag. Nat. Plist. ser. 2, vol. xvi, 



1855, p. 88, pi. V. fig. 14. (Not B. Muccoyiana, Jones, ibid. ser. 3, 



vol. i. 1858, p. 252, pi. x. fig. 15, which is B. pennsylvanicay ibid. 



p. 253, retaining the marginal frills absent in figs. lG-18.) 

 Beyrichia Maccoyana, Boll, 18G2, Archiv Ver. Freunde Naturg. Mek- 



lenburg, 16. Jahrg. p. 134, pi. O. fig. 9. 

 Bei/richia Mans (?), Boll, 1856, Zeitschr. d. d. geol. Ges. vol. viii. p. 323, 



tig. 4 ; and 1862, Archiv &c. p. 136, pi. O. tig. 11. 

 Beyrichia Maccoyana, Heidenhaiu, 1SG9, Zeitschr. d. d. geol. Ges. 



vol. xxi. p. 17], pi. i. fig. 13. 

 Beyrichia Maccoyana, Krause, 1877, Zeitschr. d. d. geol. Ges. vol. xxix. 



p. 34, pi. i. fig. 16 a, b. 

 [We are not inclined to admit as synonyms B- Dahnania^ia, Jones, and 



B. e/er/ans, Boll, as suggested by l)r. A. Krause, oj). cit. pp. 34, 35.] 

 Beyrichia Maccoyana, Kolmodin, 1879, QCfvers. K. Yetensk.-Akad. 



Fordbaudl. vol. xxxvi. p. 138 (not all the synonyms). 

 Beyrichia Maccoyana, et varr., Renter, 1885, Zeitschr. d. d. geol. Ges. 



vol. ixsvii. p. 043, pi. xxvi. figs. 16-18 c. 



(Tig. 11: L. 22. H. 15. Th. 14. 

 Proportions : \ Fig. 12 : L. 19. H. 12. 

 (Fig. 13: L. 22. H. 16. 



Several specimens, from the Upper-Silurian Shales, in 

 Messrs. Smith's and Vine's collections, are sufficiently similar 

 in character and features to allow us to refer them to this 

 Scandinavian species. In these English examples the hinder 

 lobe is large and pyriform, uniting below by a definite curve 

 with the middle lobe, and the anterior lobe, also pyriform 

 but smaller, comes down and touches their connecting isthmus. 

 The " middle " lobe is occasionally somewhat excentric 

 (fig. 12). ^ 



The surface is punctate, but more often reticulate, like 

 the impressions on the head of a thimble, but much more 

 delicate. The radiate marginal fringe or frill is more dis- 

 tinct in some individuals than in others, and this in adults is 

 really not the margin itself but a free flap s})reading outwards 

 from the valve above it. It is often unequal in breadth in its 

 semicircular extension, and projects outwards and downwards, 



