Palceozoic Bivalved Entomostraca. 187 



Measurements in lOOOths of an inch : — 



Leugth. Height. Thickness. 



Large individual (fig. 6 a). 46 20 18 



Var. omZis (fig. 7). ... 42 20 20 



Carapace small, smooth, convex, acute-ovate ; not quite so 

 much arched on the ventral as on the dorsal margin ; highest 

 near the middle, but sloping off more gently to the anterior 

 end, which is sharper and slightly more compressed than the 

 posterior. The left valve (taking the most compressed moiety 

 of the valves as the anterior) is larger than the other and 

 overlaps it all round. 



A more decidedly oval form (that is, with equal ends) is 

 shown by fig. 7 (var. ovalis). 



B. concinna has some features in common with B. cuneola 

 of the Carboniferous formation, but is quite distinct in other 

 respects (Ann. & Mag. Nat. Hist. Oct. 1886, p. 250, pi. vi. 

 figs. 3-7). 



Some rather obscure, subcylindrical, long-oval, internal 

 casts of small valves, much like those of the above-mentioned 

 form, were described in the Ann. & Mag. Nat. Hist. ser. 4, 

 vol. iii. 1869, p. 212, woodcut fig. 1, as Cy there Grind- 

 rodiana ; but the latter are too small to be matched exactly. 

 These little casts were from the Woolhope Shales of West 

 Malvern. 



/-Smith Coll. no. 61 (fig. 6). Stoke-Saye, near 

 Nine J the Craven Arms, 



specimens : y 62 (fig. 7). Railway-cutting, 



(_ side of Severn, Ironbridge. 



Also from the Aymestry Limestone, Chance's Pitch, Led- 

 bury {Dr. HoU). 



7. Bythocypris Phillipsiana (Jones & Holl). 

 (PI. V. figs. 3 a, 3 5, var. major ; figs. 4 a, 4 &, 4 c, typica.) 



1869. Bairdia Phillipsiana, J. & H., Ann. & Mag. Nat. Hist. ser. 4, 

 vol. iii. p. 213, pi. xiv. fig. 7. 



Length. Height. Thickness. 

 p ,. /Fig. 3: 27 16^ 14 



Proportions: I j,j-^ 4^ 22^ 14 8 



Measurements in lOOOths of an inch : — 



■j^. of Left valve 5Q 33 



^'S'-"^ I Right valve 53 27 



r Left valve 48 27 



Fig. 4< Right valve 45 22 



(, Thickness of carapace . . . 17 



13* 



