Prof. T. Rupert Jones — Fossil Bivalved Entomodraca. 103 



IV. Fossil Ostracoda from Shotover, near Oxford. 



§ 1. Locality. — Visiting the old stone pits of Shotover Common, 

 March 16, 1874, in company with some students and Mr. H. Caudell, 

 the late Professor Phillips' able assistant, and still attached to the 

 Geological Department of the Oxford University Museum, the 

 writer was present when Mr. Caudell picked up some fossiliferous 

 pieces of the ironstone. One fragment of sandstone exhibits on its 

 bed-plane the casts of a small Unio (U. subtruncatus ^) , of a small 

 Cyrena (C. media ?), and of numerous Ostracods ; and a fragment of 

 ironstone (from a crack in sandstone) bears numerous casts and 

 impressions of small crushed Paludinoe iP. Sussexiensis'^), together 

 with a few Fish-bones. These specimens are from the "Ironsands" 

 just within the field-gate, near the "h^" on the Geological Survey 

 Map, on the Common, about 3 miles east of Oxford. They will be 

 deposited in the University Museum. 



The occurrence of so-called " Cyprides " in these Ironsands of 

 Shotover and neighbourhood had been often spoken of, but was still 

 doubtful ; see Prof. Phillips's " Geology of Oxford," 1871, p. 412. 

 Cavities left by the removal of the oolitic grains so common in the 

 Ironstone look like the impression of these little fossils ; and the 

 partly exposed convex casts of the whorls of small Paludince often 

 resemble their subovate valves. In the piece of very fine-grained, 

 ferruginous, and micaceous sandstone containing the internal cast of 

 a TJnio and impressions of a small Cyrena (?), ornamented with 

 delicate concentric ridges, numerous casts and impressions of different 

 kinds of Bivalved Entomostraca are plainly visible. 



It is not easy, however, to master the details of form and orna- 

 ment of all the little Cypridiform Entomostraca present ; inner 

 moulds and exterior casts, more or less imperfect, being bad 

 material to work upon, chiefly on account of the imperfection of the 

 outlines of the imbedded specimens. 



There seem to be five distinct recognizable forms, shown in the 

 accompanying Plate by Figs. 3-11. 



Besides the difficulty of defining outlines and other features, we 

 cannot easily assign specific names to these forms, because we are 

 not yet well acquainted with the limits of variation among the 

 several Cypridiform species found in the Purbeck and Wealden 

 formations. 



§ 2. List of the Ostracodous Entomostraca Jcnown in the Purbeck- 

 Wealden Formation. 



The recorded species of Ostracoda known in the Purbeck- Wealden 

 deposits are — 



I. — Cypris faba,Sowevhj (not Desmarest), "Mineral Conchology," 

 tab. cccclxxxv., 1824, p. 136-8 ; and mentioned also in the descrip- 

 tion of tab. xxxi., p. 78, as occurring in the Petworth Marble. This 

 was afterwards named Cypris Valdensis by Fitton and Sowerby. 



II. — 1. Cypris Valdensis, Fitton, Trans. Geol. Soc, ser. 2, 1837, 

 vol. iv. pp. 177, 205, 228, 229, 259, 260, 297, 344, and 352, pi. 21, 

 fis. 1. 



