CYTHERE. 25 



21. Cytheke oonoinna, Jones. 



CTTHEEii CONCINNA, Jones. Monogr. Tert. Entom., 1857, p. 29, pi. iv. fig. 7 ; Brady, 



Trans. Linn. Soc, 1868, p. 408, pi. xxvi, figa. 28— 

 33 ; pi. xxxviii, fig. 7 ; B., C, and R., Monogr. Post- 

 Tert. Entom., 1874, p. ICO, pi. iv, figs. 1—16. 



The numerous localities where this species has been met with, either recent 

 (North Atlantic and Arctic Oceans) or fossil (British area, Canada, and Norway), 

 are enumerated in the memoirs referred to above. (British Museum.) 



22. Cythere LiESA, Jones Sf Sherhorn. Plate III, figs. 1.3 a, h. 



Ctthebe l^sa, Jones S{ Sherhorn. Geol. Mag., 1887, p. 390. 



Ovate-oblong, straighter on the ventral than on the dorsal edge. Close to the 

 ventral margin is a broad, longitudinal, somewhat sinuous ridge, widened, or 

 rather doubled, with an oval interspace, at its posterior third, and irregular at the 

 anterior third. In one specimen the surface is coarsely reticulate with angular 

 meshes ; in the other, the ornament consists of a smaller meshwork. In this 

 latter individual the edge-view is less convex than in the other. 



From the Norwich Crag of Bramerton. Collected by Mr. Clement Reid, 

 F.G.S. (Mus. Pract. Geol.) 



23 and 23*. Cythere villosa, O. 0. Sars ; et Var. 7iov. Plate I, figs. 4 a, ft (var.) ; 



and Plate III, figs. 12 a, b, c. 



Ctthehe villosa, Brady, Orosshey, 8f Boberfson. Monogr. Post-Tert. Entom., 1874, 



p. 157, pi. iii, figa. 7 — 13 ; Jones 

 and Sherborn, Geol. Mag., 1887, 

 p. 390. 



Subtriangular, straight on the ventral, and obliquely arched on the dorsal and 

 front edges, but somewhat truncate behind. Surface bearing a somewhat con- 

 centric reticulation of coarse angular pittings. Three unequal tubercular swellings 

 affect the valve just within its thickened rim, two behind (fig. 12 c), such as are 

 frequent in this group of Gytherse, and one in the antero-ventral third. The 

 greatest convexity of the valves is central, making the edge-view acute-oval. 



4 



