CYTHERIDEIS. 45 



recent; and C. sphenoides (Reuss), ' Denkschr. k. Akad. Wiss. Wien,' vol. vii, 1854, 

 p. 141, pi. xxvii, fig. 2, from the Chalk of the Eastern Alps. 



From the London Clay of Copenhagen Fields and Piccadilly (British Museum), 

 and from the Chalk of Mecklenburg and the Dobrudscha. 



XX. CYTHERIDEIS, Jones, 1857. (Restricted.) 

 Monogr. Tert. Entom., 1857, p. 46. 



1. CYTHERIDEIS COLWELLENSIS, Jones. 



Cytheeideis Colwelleistsis, Jones. Monogr. Tert. Entom., 1857, p. 49, pi. iv, figs. 13 and 



20; Oythere?, Geol. Mag., 1870, pp. 157 and 159. 



This (with the left valve larger than the right), now retained in Gytherideis, 

 occurs at Colwell Bay in the Nucula-bed (Nucula deltoidea) and other deposits, but 

 not abundantly. (British Museum.) 



2. Cytheeideis botellina, Jones, 



Cytheeideis elavida (Milller). Jones, Monogr. Tert. Entom., 1857, p. 50, pi. iv, 



figs. 4 a — c. 

 Cytheee botellina, Jones. Geol. Mag., 1870, p. 157. 



According to Dr. G. S. Brady, Midler's C. fiavida differs materially from this 

 Crag species. Dr. Baird's C. fiavida is referred to Cytherideis subulata by Brady 

 (' Trans. Linn. Soc.,' vol. xxvi, 1868, p. 454, pi. 35, figs. 43 — 46), which also 

 differs from the species under notice. The new specific name was therefore 

 proposed in 1870. C. botellina is known only from the Crag of Suffolk, where it 

 is abundant. (British Museum.) 



3. Cytheeideis, sp. 



Monogr. Tert. Entom., 1857, p. 51. 



A form somewhat related to Cytherideis botellina, Jones, but shorter, occurs 

 in the Tertiary Sands of Colwell Bay. It is referred to in the ' Monograph,' loc. 

 cit. Possibly it may be C. gracilis. (British Museum.) 



