from the " Cambridge Greensand." 339 



Cythereis quadrilatera (Romer). 



Cytherina quadrilatera, Romer, 1840, Verstein. norddeutsch. Kreidegeb, 



p. 105, pi. xvi. %. 19. 

 Cythereis quadrilatera, Jones, 1849, Mon. Entom. Cret. p. 18, pi. iii. 



figs. 10«-/, pi. iv. figs. 10 q-j' ; Jones andHinde, 1890, Suppl. Mon. 



Cret. Entom. pp. 20, 21, pi. 'i. figs. 69-75. 



This species is represented in the Cambridge Greensand ot 

 Swaffham by several well-grown individuals and numerous 

 young specimens, which in some cases are difficult to separate 

 from G. Lonsdaleana, Jones. It is a persistent form nearly 

 throughout the Cretaceous formation, and it has also been 

 recorded from the Great Oolite and Lower-Greensand beds 

 of the Richmond well-boring. Cythere orchidea of Bosquet* 

 is perhaps comparable with some young individuals of 

 Cythereis quadrilatera. 



Cythereis ornatissima (Reuss). 



Cytherina ornatissima, Reuss, 1846, Verstein. bohni. Kreidef'orin. pt. ii. 



p. 104, pi. xxiv. figs. 12, 18. 

 Cythereis ornatissima, Jones and Hinde, 1890, Suppl. Mon. Cret. 



Entom. pp. 21, 22, pi. ii. figs. 1-7, 15, 16, pi. iv. figs. 7, 8. 



The earliest appearance of this species is in the Lower 

 Greensand of Surrey (Chapman). It is a very characteristic 

 form throughout the succeeding strata to the Chalk. It has 

 been noticed in the Cambridge Greensand and it is not un- 

 common at Swaffham, although there, as in other strata, the 

 varieties are more frequently met with. 



Cythereis ornatissima (Reuss), var. paupera, Jones and 

 Hinde. 



Cythereis ornatissima (Reuss), var. paupera, Jones and Hinde, 1890, 

 Suppl. Mon. Cret. Entom. p. 23, pi. ii. figs. 10, 11. 



This variety has been obtained from the Chalk-rock. 

 Several specimens were found in the Greensand of Swaffham. 



Cythereis ornatissima (Reuss), var. nuda, Jones and Hinde. 



Cythereis ornatissima (Reuss), var. nuda, Jones and Hinde, 1890, Suppl. 

 Mon. Cret. Entom. pp. 23, 24, pi. i. fig. 76, pi. ii. figs. 9, 12-14, 

 pi. iv. fig 14. 



The range of this variety is from the Gault to the Upper 

 Chalk. It has also been observed in the Cambridge Green- 

 sand by Messrs. Jones and Sherborn (Vine coll.). 



Three separate valves of this variety were found at 

 Swaffham. 



* Mem. Comm. geol. Neerlande, 1854, vol. ii. p. 98, pi. vi. a-d. 



