412 



Prof. T. R. Jones on the 



Vine Coll. : 



Figs. 5 & 9: no. xix. 

 Fig. 7 : XX. 



Fie:. 8 : xxi. 



} 



Bedsno.25&25*. 



Tickwood 



Beds. 



Specimens : f 

 cusjndata, 8 [ 



bovina, 3 J 



depressicornts , 1^ 

 hrevicornis, 1 

 obscura, 2 



Mr. John Young and Mr. Vine met with fragments of spines 

 and valves in Bed no. 46, shales over Wenlock Limestone. 



f Smith Coll. Figs. 2, 3, & 4, no. 41. Wool- 

 hope. 

 No.*46. Rail way- cutting, Coal- 

 brook Dale. 



Specimens : 

 cuspidata^ 10 

 bovinUy 2 



Fig. 6, no. 47. Railway-cut- 

 ting, Severn side, Ironbridge. 



2. ^chmina bovina. 



sp. 



nov. 



(PL XIII. figs. 5 a, 5 ^', 5 c, 6 a, 6 J, 6 c.) 



Proportions : — 



Fig. o : 

 Fig. 6 



Length. 

 18i 

 13^ 



Height. 

 11 

 9 



Thickness at 



root of the 



spike. 



n 



7i 



Width be- 

 tween the 

 tips. 



Length of 

 spike. 



10 



10 15i 



m 



The carapace-valves have a straight dorsal and nearly 

 semicircular ventral border. The hollow spike or horn is 

 thicker than in ^ch. cuspidata, its base taking up a larger 

 portion of the valve's surface ; it is also shorter, and has a 

 slight curve upwards and inwards. The angle of divergence 

 of the spikes in the closed valves is, (1) from the top of the 

 valves to the point of horn 45°, (2) from the middle of the 

 front of the valves to the point of the horn 66° to 60°. In 

 some specimens there is a tendency to have the base of the 

 spike somewhat contracted or depressed before it rises above 

 the surface. Seen endwise the carapace, with its valves 

 united (tigs. 5 J, 6^^), reminds us of the aspect presented by 

 the face and front of some of the Bovidai, whilst figs. 3 b and 

 4 5 of ^ch. cuspidata have more analogy to the long straight 

 horns of some antelopes, such as the Oryx and Anoa. 



^ch. bovina approaches jEch. clavidus, J. & H. (Ann. & 

 ]\[ag. Nat. Hist., I. c, woodcut, fig. 2), in some respects, but 

 the base of its hollow spike takes up much less space on the 

 valve. In yEch. davulus, indeed, the base of the spike is 

 conterminous with the margins of the valve, whereas in the 

 other it carries out with it only about a third of the surface or 

 a little more. 



