CYTHERE BAIRDIANA. 15 



curved dorsal, and concave ventral border; convexity moderate and uniform. 

 Edge view long-oval ; end view subcircular. 



Locality. — Collected by Mr. Joseph Wrigbt, F.Gr.S., from the powder of a 

 hollow flint (ChalJc) at Black Hill, co. Antrim ; also at Slieve Gallion, co. London- 

 derry. 



Gytherina laevigata, Romer, as figured by Reuss in Haidinger's ' Naturw. 

 Abhandl.,' vol. iv, I Abtheil., p. 49, pi. vi, fig. 6, from the Chalk-marl of Lemberg, 

 is also bent and equal-ended, but the outline is not nearly so convex above 

 (dorsally), nor so concave below (ventrally), as in fig. 31. The figure of the 

 Tertiary C. Imiata, Romer, ' N. Jahrb.,' 1838, p. 517, pi. vi, fig. 18, has its ends 

 very much too sharp for the species under notice. 



II. CYTHERID^. 

 I. Cytherb, Mailer, 1785. 



See Supplem. Monogr. Tert. Entom., 1889, p. 12. 

 § I. Oblong forms, with nearly uniform convexity ; punctate or reticulate. 



1. Cytheee ? BosQUBTiANA (JoTies). Plate II, figs. 35 — 37. 



Cythebella ? BosQUETiANA, Jones. Monogr. Eatom. Cret., 1849, p. 33, pi. vi, 



figs. 23 a — c. 

 CxTHEHE BosQTJETiANA, Joncs. Geol. Mag. 1870, pp. 76, 77. 



Length 'QQ ; height "27 ; thickness "22 mm. 



The unique carapace from the Charing Detritus has not been represented by 

 any other specimen, and we can add nothing to the former description. 



2. Cytheee Bairdiana, Jones. Plate I, figs. 30 — 32. 



Cytheee Baibdiana, Jones. Monogr. Entom. Cret., 1849, p. 13, pi. ii, figs. 5 a — c. 

 — TKANSiENs (?), Joues. Quart. Jouru. Greol. Soc, vol. xli, 1885, p. 349, pi. 



ix, figs. 13— lU. 



Length -63; height '36; thickness '33 mm. 



This unique specimen of a right valve was from the Greensand of Faringdon, 

 Berks; and, though somewhat obscured by fossilization, is so much like Cy there 

 transiens, Jones, from the Lower-Purbeck beds at Swindon, and the Portland beds 



