340 Mr. F. Chapman on Ostracoda 



Cythereis omatissima (Reuss), var. reticulata, Jones and 



Hinde. 



Cythereis omatissima (Reuss), var. reticulata, Jones and Hinde, 1890, 

 Suppl. Mon. Cret. Entom. p. 24, pi. i. figs. 67, 68, 77, pi. iv. figs. 9-12. 



This form is by far the commonest variety of the group of 

 Ostracoda of which C. omatissima is the type ; and this is 

 especially so of the lower part of the Upper Cretaceous, where 

 it is apparently at home in the more shallow-water deposits 

 of this part of the formation. In such deposits the carapace 

 often exhibits a striking redundancy of shell-growth. 



Its earliest appearance is probably in the Lower Green- 

 sand of Surrey, and its range extends to the Upper Chalk. 



C. omatissima, var. reticulata, has already been recorded 

 from the Cambridge Greensand, and it is very common in 

 the material from SwafFham. 



Cythereis omatissima (Reuss), var. radiata, Jones and 

 Hinde. 



Cythereis omatissima (Reuss), var. radiata, Jones and Hinde, 1890, 

 Suppl. Mon. Cret. Entom. p. 25, pi. iv. tig. 13. 



This unique variety was described by the above authors 

 from a specimen in the Vine collection from the Cambridge 

 Greensand. 



It has not been met with at S waff ham. 



Cythereis omatissima (Reuss), var. stricta, Jones and Hinde. 



Cythereis omatissima (Reuss), var. stricta, Jones and Hinde, 1890, 

 Suppl. Mon. Cret. Entom. p. 25, pi. i. fig. 63. 



Previously described from the Chalk-marl of Didcot and 

 the Upper Chalk of Swanscombe. It is represented in the 

 series from SwafFham by three individuals. 



Cythereis Wriqhtii, Jones and Hinde, var. aculeata, 

 Chapman and Sherborn. 



Cythereis WrighUi, Jones and Hinde, var. aculeata, Chapman and Sher- 

 born, 1893, Geol. Mag. vol. x. p. 349, pi. xiv. fig. 9. 



The original specimens were from the Gault of Folkestone. 

 One specimen of C. Wrightii, var. aculeata, was found in 

 the Cambridge Greensand of SwafFham. 



Cythereis tuberosa, Jones and Hinde. 



Cythereis tuberosa, Jones and Hinde, 1890, Suppl. Mon. Cret. Entom. 

 'p. 26, pi. iii. figs. 2, 3. 



A specimen resembling very closely that originally described 

 and figured from the Upper Chalk of Norfolk was found in 

 the Greensand of SwafFham. 



