406 Prof. T. E. Jones on the 



1******. Var. monticulata, nov. 

 (PI. XII. figs. 8 a, 8 J.) 



Proportions:— L. 251. H. 14. Th. 12. 



Here we have tlie encircling oval ridge perfect and simple, 

 and an isolated tubercle within and near its antero- ventral 

 portion, just where the thickened inturned end is present in 

 fig. 3 a. It is homologous also probably with tlie local 

 thickenings in the other varieties. 



( Vine Coll. no. xvig. Bed no. 46. Shale over 



Two J Wenlock Limestone, 



specimens : j LXV3. Shale over Wenlock 



(_ Limestone. 



In LXV2 and LXVijj, 14 there are five obscure specimens of 

 Oct07iana. 



2. Octonaria undosa, sp. nov. 

 (PI. XIL figs. 1 a, 1 h.) 



Proportions :—L. 35. H. 15^. Th. 12. 



This relatively long valve has nearly parallel dorsal and 

 ventral edges and obliquely rounded unequal ends. The sides 

 slope strongly to the margin all round. The anterior ex- 

 tremity is obliquely produced and more compressed than the 

 other. The middle of the valve is raised into an obscure and 

 imperfect figure-of-eight, the loops being open along the dorsal 

 region (as fig. 4 might be, if the ridge were dorsally imper- 

 fect) ; or it may be said to be raised nearly flat, with two 

 shallow bay-like dorsal impressions, and a middle ventral 

 inlet, altogether giving a rough figure-of-three if looked at 

 with the anterior end upwards. The edge view of the two 

 valves closed would approximate to that of other Octonarue, 

 but with sharper ends. 



One specimen : — Smith Coll. no. 70. Lincoln Hill, Iron- 

 bridge. 



3. Octonaria^ paradoxa, sp. nov. 

 (PI. XIII. fig. 12.) 



Proportions :— L. 20. H. 10. 



This peculiar form may probably belong to the Octonarian 

 group, though differing very much from the species above de- 

 scribed. The valve, however, is raised into a thick, smooth, 

 figure-of-three ridge, somewhat like that in PI. XII. fig. 1 ; 

 and the isolated tubercle has an analogue in fig. 8. The ab- 

 sence of a broad sloping margin is observable. The dorsal 



