the Palceozoic Bivalved Entomostraca. 



219 



into the depressed area along the straight edge, thus forming 

 three unequal lobes on the dorsal region, the rest of the valve's 

 surface remaining smoothly convex, bordered by a narrow 

 depressed rim. 



The shape of the valve is that common among Primitice j 

 but, though the sulci are too short for those usually charac- 

 teristic of BeyricMce (excepting B. Wilchensiana., Jones, Ann. 

 Nat. Hist. ser. 2. vol. xvi. pi. 5. figs. 17 & 18), yet we are 

 unwilling to admit a bisulcate form among the " Primitim " 

 until further evidence proves the necessity of breaking down 

 the provisional limitation of that genus. In the meantime we 

 regard the pretty little specimen before us as an intermediate 

 form, as its name intimates. 



Our figured specimen is from the Aymestry Limestone of 

 Chance's Pitch, Mlilvern, where specimens are not uncommon ; 

 and some few casts of apparently the same species occur in Wool- 

 hope Shale from near Malvern, in Dr. Grindrod's collection. 



1. Primitia lenticularis^ sp. no v. Woodcut, fig. 4 «, />, c. 



Carapace smooth or slightly rugose (perhaps from weather- 

 ing), convex, nearly ovate ; elliptically rounded below, decidedly 

 arched above, unequally rounded at the ends ; the larger (pos- 

 terior) extremity with a marginal rim and compressed ; ventral 

 border slightly lipped. Dorsal aspect elongate-ovate, rather 

 compressed in front of the centre, and acute posteriorly. End 

 view subacute-oval. 



This is near to P. ouato, J.& H. Ann. Nat. Hist. ser. 3. vol. xvi. 

 p. 423, pi. 13. fig. 13, and P. ohsoleta, J. & H. he. cit. fig. 12, 

 iDOth Scandinavian. It is shorter, however, more convex, and 

 more ovate (being higher as 32 : 30, and shorter as 43 : 45) 

 than the former, and it has a posterior marginal rim, with very 

 little of it continued on to the ventral border ; it has also a 

 different edge view, being less compressed anteriorly. From 

 P. ohsoleta it differs in having an arched dorsum, much less 

 marginal rim, a more central convexity, and no trace of dorsal 

 sulcus. 



b c 



Fig. 4. Primitia lenticularis : a, carapace, showing the right valve ; 



b, dorsal view of carapace ; c, end view of carapace. 



(MaguiHed 20 diameters.) 



Common in the calcareous beds at the base of the WooDiope 

 beds near Malvern. 



