452 Jones and Sherhorn— Tertiary Entomostraca. 



does not appear to us to be at all identical), and also C. pumila, G. 

 S. B., op. cit., p. 378, pi. Ix. jfig. 7. The latter, though near to our 

 specimen, has far more irregular ridges. 



One valve, from the " Norwich Crag" of Southwold. T. E. Jones'' 

 Collection. 



35. Ctthere sobobiculo-plicata, Jones. PI. XI. Fig. 8. 



A figure of this species is reproduced from " Monograph Tert. 

 Entom.," 1856 (p. 33, pi. vi. figs. 4 and 6), as one of the forms 

 belonging to the London Clay of Finchley and Copenhagen Fields ; 

 the species also belongs to the Barton Clay, in which deposit it 

 occurs in greater abundance than in the London Clay. 



36. Cythere Harkisiana, Jones. Woodcut Fig. 1. 



Cythereis interrupta, Jones. Monngr. Cretac. Entom., 1849, p. 16, pi. ii. f. 6. 

 Cythere Harrisiana, Jones. Geol. Mag., 1870, pp. 75, 76. 



This form was found with C. spinosissima, here- 

 after described, while looking over for a second time 

 some washings of London Clay. We have only this 

 one valve, which agrees so closely in every particular 

 with valves from the Gault, presenting the same 

 isolated prickles and the pursed-up posterior end with 

 its flattened margin, that we cannot separate them. ^ 



Sherborn and Chapman Collection ; from Picca- Sarrisiana Jones! 

 dilly, London. 



37. Cythere Forbesii, sp. nov. 



A subquadrate form, approaching the more definitely squared 

 CythercB, for which we conveniently keep the subgeneric name of 

 Cythereis. The valves are well-rounded in front and behind, with 

 nearly straight lower and upper margins, the latter marked with 

 well-defined hinges. The posterior margin is usually denticulate. 

 The surface bears 6 or 7 crenulate and fenestrate ridges ; those on 

 the ventral region being more continuous than those on the dorsal. 

 The interspaces of the ridges are deeply reticulated. This distinct 

 and well-defined species we dedicate to the late Edward Forbes, 

 whose investigations into the fossil fauna of the Isle of Wight 

 Tertiaries will ever be gratefully remembered. 



Specimens numerous, from the Fluvio-marine beds of Headon, Isle 

 of Wight. F. Edwards' Collection in the British Museum. 



38. Cythereis Bowerbankiana, Jones. PI. XI. Fig. 9. 

 Monogr. Tert. Entom. 1856, p. 38, pi. vi. figs. 7 and 8. 

 A figure of this quadrate species, characteristic of the London 

 Clay, is here reproduced in illustration of the group. It has been 

 found at Copenhagen Fields and Wimbledon Common (Jones), and 

 at Whiteclifi" Bay (Sherborn). 



39. Cythereis spinossissima, sp. nov. Woodcut, Fig. 2. 

 A right and left valve of this form were lately found, with C. 

 Harrisiana, in some washings of the London Clay from Piccadilly. 

 They are oblong, with the front margin broader and more semi- 



