CYTHEROPTERON PEDATUM. 39 



Cytueke (Cytueeeis) cuspiuis, Jones, MS. System. Lists, &c., Belfast Nat. 



Field Club, vol. i, Appendix iii, 

 1875, pp. 81, 92. 



Length 1*26; height 'SS ; thickness (with spines) 1'2 mm. 



Suboblong, with obhque ends, rounded in front, acute behind ; surface convex ; 

 depressed, margined, and denticulate in front; rising to a strong spine at the 

 posterior third, and suddenly sinking behind to a contracted, flat hinder margin ; 

 bordered ventrally with a narrow raised rim. The surface is punctate, and, 

 together with the dorsal edge, bears small irregular prickles. The large spine 

 points backwards, but its angle varies. In the Irish specimens it stands out more 

 boldly than in Dr. Marsson's figures, two of which (figs. IG h and c) illustrate his 

 smooth variety " Isevis." 



Localities. — GhalJi, Horstead (Norfolk), near the Gobbins (Antrim), and Keady 

 Hill (Londonderry) ; Chalk-rock, Dunstable. 



7*. Cytheeopteeon pedatum, Marsson, var. salehrosa, nov. {velpedatum-salebrosum). 



Plate III, fig. 8 ; Plate IV, fig. 32. 



PI. Ill, fig. 8. Length -87 ; height -4 mm. 



PL IV, fig. 32. „ 1-0; „ •406 mm. 



Subtriangular, rounded and denticulate in front, obliquely subacute behind, 

 with a narrow, flattened end. The dorsal edge is straight, and the ventral nearly 

 parallel with it. Margined with a raised rim all round except where it is tubercu- 

 late on the postero-dorsal edge. At the dorsal region the surface is impressed 

 with three shallow, nearly equidistant, transverse furrows ;^ the middle one 

 largest, and the foremost weakest. Thus the surface of the body of the valve 

 undulates with four low transverse swellings and three corresponding valleys. 

 The whole surface is rough with irregular granulations, interspersed with small 

 tubercles, and the thick, short spine rises from the posterior of the two main 

 transverse swellings. 



This has the look of Cijtherojyteron jyedatum as to outline, and possesses a 

 short, thick spine, rising on the posterior moiety of a rough and undulating valve. 

 It somewhat resembles Reuss's Gythere oxyiira from the Cretaceous Baculite-clay 

 at the Kanara Lake, near Kustenjeh in the Dobrutscha,^ ' Sitzungsb. Akad. Wiss. 

 Wien,' vol. Hi, p. 24, pi. — , fig. 13. 



^ Not well showu in fig. 82. 



^ See also ' Quart. Journ. Geol. Soc.,' vol. xiv, p. 20G, &c. 



