CYTHERE. 19 



XL CYTHERE, Mullcr, 187b. 



Valves unequal (left valve usually somewhat larger than the right), oblong- 

 ovate to quadrate in shape, smooth or rough, mostly highest in front ; hinge with 

 teeth and sockets at anterior and posterior angles, variously developed. 



The quadrate and rough forms have been classed as Cythereis (' Monogr. 

 Oetac. Entom.,' 1849, p. 14) ; and, although this group will not hold its own as 

 a true genus, Dr. G. S. Brady having shown that the animals do not sufficiently 

 differ from other Cytherce, 1 yet it is a very convenient grouping for palaeontologists, 

 who have for study only the valves of these small fossil Crustacea. 



1 . Cythere convexa, Baird. 



Ctthere punctata (non Miinster). Jones, Monogr. Tert. Entom., 1857, p. 24, pi. 



ii, figs. 5 a— h; Geol. Mag., 1870, p. 156. 

 — convexa, Baird. Brady, Traus. Linn. Soc, 1868, p. 401, pi. xxix, figs. 



19 — 27, and pi. xxxix, fig. 4 ; Brady, Crosskey, and 

 Kobertson, Monogr. Post-Tert. Entom., 1874, p. 150, 

 pi. iii, figs. 14 — 17. 



Owing to the poorness of the published figures of the German specimens, Dr. 

 G. S. Brady is unwilling to accept Miinster' s appellation for the Cy there repre- 

 sented in the Monograph under the name of " punctata," and refers it (' Trans. 

 Linn. Soc,' 1868, p. 401) to Cy there convexa, Baird. Fig. 5 a (broken posteriorly) 

 differs, however, from the usual C. convexa in its concentrically ridged anterior 

 region and its very coarse punctation. (British Museum.) Cypridina punctatella, 

 Reuss (Cythere punctatella, Bosq.), referred to in the synonymy at p. 24 of the 

 'Monograph Tert. Entom.,' belongs to Loxoconcha, according to Dr. Brady. 



2. C trigonula, Jones, 1856, from the Crag, is the next in order. (British 

 Museum.) 



3. Cythere striatopunctata, Jones. 



Cythere striatopunctata, Jones. Monogr. Tert. Entom., 1857, p. 27, pi. v, 



figs. 6, 7, 10. 



This species has been found at the base of the Barton Clay at Alum Bay, in 

 t he Bed " No. 29 " of Prof. Prestwich's section (' Quart. Journ. Geol. Soc,' vol. ii, 



1 ' Trans. Linn. Soc.,' vol. xxvi, p. 395. 



