Paheuzoi'c Bivalved Entomostraca. 179 



belong to the Cjtheridse or to the Cjpridid£e it is often 

 difficult to say ; but the genus Cythere comprises very few of 

 the smooth subovate forms, and none that have toothless 

 hinges. Hence we find that a real Cythere is scarcely known 

 in Pakeozoic strata ; and when the term is applied to such old 

 forms it is in a very general and probably artificial sense. 



1. Macrocypris Vinei, sp. nov. 

 (PI. IV. figs. 1, 2, 3 J and woodcut.) 



1882. ''' Bairdia elongata, Munster(?)," Vme, Quart. Journ. Geol. Soc. 

 vol. xxxviii. p. 48. 



Macrvci/i>ris Vinei, sp. nov. Thick variety ( § ?). Magn. 26 diam. 

 Vine Coll. lxv,. Bed no. 46. 



Length. Height. Thickness. 



C Fig. 3 : 41 14 13 



r» ,• * ) Woodcut: 40* 13 



lroportions*:^pjg_j. 3^- ^3 ^^ 



(Fig. 2: 33 10 9^ 



Measurements of some specimens in lOOOths of an inch : — 

 Length. Height. Thickness. 



80 29 25 Vine Coll. Bed no. 40. 



80 23 20 Vine Coll. Bed no. 46. 



75 27 22 Vine Coll. Bed no. 46. 



65 24 18 Smith Coll. Railway, Ironbridge. 



Carapace smooth, nearly equivalved, elongate, subcylin- 

 drical, tapering at each end ; rounded and compressed in front, 

 obliquely acute at the postero- ventral extremity ,• arched 

 above, nearly straight below. In some cases the dorsal edges 

 fall in a little, so that tlie middle of the back is slightly flat- 

 tened. The ventral edge of the left valve slightly overlaps 

 its fellow, and sometimes an overlap by the right valve on the 

 dorsal edge is discernible, but not so strong as in most of the 

 recent species. Some indications of a rose-shaped muscle- 

 spot are visible. 



Soc. xxvi. 1868; the " Monograph of thePost-Tertiary Entomostraca," &c., 

 by Brady, Crosskey, and Kobertson, Palteont. Soc, 1874 ; and Dr. Bradv's 

 "Report on the Ostracoda of the 'Challenger' Expedition," 1880, 



• If these proportioual ininibers be divided by I'o, tlie results will ht^ 

 the real ineasureuient:? in niillimetres and parts uf a niilliinelre. 



