Palceozoic Bivalved Entomostraca. 411 



Dudley Tminel. In nos. 26 and 78, raihvay-cuttino-, side of 

 Severn, Ironbridge, it is smooth. In the Vine Collection 

 LXVI; (part); Tickwood Beds, it is also present. 



15. Primitia cristata, Jones and Holl. 



Primitia cristata, J. & II. op. cit. figs. 1 a, b, c. 



Proportions :—L. 15. H. 11-25. Th. 11'5. 



This well-marked species is rather abundant in some of the 

 Shales (Tickwood Beds) in Vine Coll. xxx and LXVI7, in 

 both cases showing delicate toothing on the front margin of 

 each valve. 



16. Primitia ornata^ sp. nov. (PI. XIV. fig. 5.) 

 Proportions: — L. 10. H. 6. 



A small, moderatelj and equally convex, suboblong, Leper- 

 ditioid form ; straight at the back, with a long hinge-line ; 

 curved on the free edges ; the ventral longest and gently 

 curved ; ends nearly semicircular_, but the posterior boldest. 

 Surface coarsely reticulated with neat meshes and bordered 

 with a slight rim. Dorsal sulcus median and variable, some- 

 times ending in a definite central pit, sometimes represented 

 only by a subumbilical hollow. 



Though near to P. variolata, this is distinguished by its 

 sha])e, ornament, and small size. The dorsal profile of the 

 carapace is a narrow oblong with rounded ends. 



In the Vine Coll. xxiv, bed 25 ; Smith Coll. nos. 55 and 

 72, Woolhope, and no. 76 (part), Lincoln Hill, Ironbridge. It 

 is not common. 



17. Pnmitia cornuta, sp. nov. 

 (PL XIV. figs. 12a, 12 5, and fig. 13 (young).) 



r Fig. 12: L. 18. H. 10. Th. 7,andbe- 

 Proportions : ■< t ween the tips 1 1 . 



(.Fig. 13: L. 9. H.6. 



Carapace semiovate, straight on the back, elliptically curved 

 on the free edges, being semicircular behind, and broadly and 

 obliquely curved on the ventral and anterior margins up to 

 the antero-dorsal angle. Surface finely reticulate, with some 

 meshes larger here and there, forming small pits ; convex 

 behind, compressed in front, excepting that the antero-ventral 

 region of each valve bears an outstanding sharp tubercle. 

 Another, but shorter, tubercle projects from each postero-dorsal 

 region. Hence the dorsal view (fig. 12 h) gives a bluntly 

 rounded end behind, and a sharp front end, with the lateral 



