Palceozoic Bivalced Entomostraca. 193 



grounds I distinguish this oldest-known form by a separate 

 appellation — G. Smithii — after Mr. Smith, of Kilwinning, in 

 wliose collection this species is largely represented. 

 Smith Coll. (six specimens) no. 63. Woolhope. 



VI. Primitia, Jones & Holl, 1835. 



(See Ann. & Mag. Nat. Hist. ser. 3, vol. xvl. p. 415, 

 and ser. 5, vol. xvii. p. 408, &c.) 



1. Primitia j)unctataj sp. nov. (PI. VII. figs. 9 a, 9 ^.) 

 Proportions :— L. 19. H. 10. 



Long-oblong carapace, with rounded, nearly equal ends ; 

 rather small, plump, nearly oval in edge view. Surface of 

 valves marked with a faint saddle-shaped depression in the 

 mid-dorsal region, and delicately punctate, especially on the 

 posterior third. On the cast of the interior the impression 

 becomes a deep transverse sulcus, reaching nearly across the 

 valve, and with a width equal to yth of the length of the shell. 



P. punctata is found in Mr. Smith's no. 67 (four specimens) . 

 Railway-cutting near Much-Wenlock ; and Vine Coll. 

 LXVu(part) (©'"'ti specimen). Shales over the Wenlock Lime- 

 stone. Two also from no. 22. Buildwas Beds. 



2. Primitia valida, J. & H. 

 (PI. VI. fig. 7, magnified 50 diam.) 

 Primitin valida, Ann. & Mag. Nat. Hist. ser. 5, vol. xvii. (1886), p. 409, 

 pi. xiv. fig. 7. 



Proportions :— L- 22^. H. 14i. 



This well-preserved left valve, showing its hinge-line and 

 the rest of its margin of contact, and partially its interior, was 

 at first inadvertently associated with 0. UoUii (figs. 5 and 6) ; 

 but it is more quadrate and symmetrical and otherwise differ- 

 ent. So also it is much more oblong than the analogous 

 interior of P. umhilicata, J. & H. (Ann. & Mag. Nat. Hist. 

 ser. 3, vol. xvi. pi. xiii. fig. 2 d). 



In the Vine Coll. no. LXiii. Bed no. 25. Tickwood 

 Beds, Altogether there are seventeen specimens of P. valida 

 (without the varieties) in the Vine Collection and six in the 

 Smith Collection. 



VII. Incertm sedis. (PI. VI. figs. 8 a, 8 h.) 



Proportions :— L. 19. H. 10. Th. of valve 5 (of 



carapace 10). 



An oval valve with a flexuous, undulate, and broadly 



bisulcate surface ; and thus somewhat like the cast of Cythe- 



