from the. " Camhridge Greensand.^^ 341 



Cythereis Lonsdaleana, Jones. 



Cythereis Lonsdideana, Jones, Mon. Eiitom. Cret. 1849, p. 20, pi. v. 

 tigs. 1-2 a-c; Supi)l. Mon. Cret. Entom. 1890, p. 27, pi. i. figs. 40-42, 

 64-66. 



This species has been noticed in strata as old as the Upper 

 Oolite ; it also occurs in the Lower Greensand of Surrey and 

 in the Chalk-rock and Upper Chalk. 



One undoubted specimen was found in the Cambridge 

 Greensand of Swaffham. 



Cytheridea, Bosquet, 1852. 



Cytheridea perforata (Roiner). 



Cytheriim perforata, Romer, 1838, Xeues Jahrb. fiir Min. &c. p. 516, 



pi. vi. fig. 11. 

 Cytheridea perforata., Jones, 18o7, Mon. Tert. Entom. p. 44, pi. iv. 



tig. 14 ; Jones and Hiude, 1890, Suppl. Mon. Cret. Entom. p. 29, 



pi. i. figs. 1-4. 



This familiar and widely distributed species has a geolo- 

 gical range extending from the Gault (and possibly the 

 Upper Oolite) to the Oligocene of Colwell Bay. It is already 

 known as a Cambridge Greensand fossil. 



(7. perforata is a common form in the series from the 

 Greensand of Swafl'ham. 



Cytheropteron, G. O. Sars, 1865. 



Cytheropteron concentricum (Reuss). 



Cytherina concent rica, Reuss, 1846, Verstein. bohm. Kreideform. pt. IL 



pp. 104, 105, pi. xxiv. figs. 22 a-c. 

 Cytheropteron concentricum, Jones and Hinde, 1890, Suppl. Mon. Cret. 



Entom. pp. 31, 32, pi. i. figs. 5-10, pi. iv. tig. 19. 



This striking and very variable form is found in strata of 

 Lower-Greensand age in Surrey, and also in the Xeocoraian 

 of Haute-Marne, France, and from thence its range extends 

 to the Upper Chalk. 



It has already been noticed in the Cambridge Greensand. 

 In the material from Swaffham it is very abundant, and 

 presents a remarkable series of variations in the ornament of 

 the surface, ranging from those with delicate pittings and 

 the prickly meshwork in concentric lines to others with a 

 relatively coarse and wrinkled surface of sinuous furrows, but 

 without the punctules. 



Ann. lL- Mag. N. Hist. Ser. 7. Vol ii. 24 



