FROM TANGANYIKA AND KENYA 33 



threads may occupy the main intervals ; the total number anterior to the carina on 

 the left valve is uncertain, but must have exceeded 20. 



Holotype and paratype. Nos. LL.35091, LL.35092 respectively, both ex B.P. 

 Coll. 



Locality and horizon. N. of Matapwa, Pindiro area, Tanganyika ; Upper 

 Kimmeridgian. 



Remarks. This species is more nearly equilateral than G. (I.) irritans and has a 

 blunter boundary between its flank and posterior area and more numerous ribs. 

 The delicate concentric threads which form part of its ornament have not been 

 observed in G. (I.) irritans. 



Genus APOLINTER Casey 1961 



Apolinter kindopeensis sp. nov. 

 PI. 3, figs. 3a, b, 4a, b 



Diagnosis. Small, with the length (16 mm. in the larger specimen, the holotype) 

 slightly less than twice the height ; convexity moderate. Ventral margin evenly 

 convex, its general direction diverging from the hinge-margin in a posterior direction, 

 so that the shell is highest near its posterior end. Umbo broadly rounded, placed at 

 about anterior third of length of shell, protruding slightly above the hinge-margin. 

 A well-defined umbonal ridge, curved with an upward-facing convexity, runs to the 

 postero-ventral corner of the shell and delimits a narrow, concave posterior area. 

 Hinge-margin about three-quarters of length of shell ; postero-dorsal angle obtuse. 

 It is evident that the ligamental area, although not seen in available specimens, was 

 narrow, and that the umbones of the two valves were very little separated. Orna- 

 ment of regular, close-spaced, depressed concentric ribs. 



Holotype and paratype. Nos. L. 56243, L. 56244 respectively. 



Locality and horizon. Kindope, 2 miles N.N.W. of Tendaguru, Tanganyika. 

 Upper Kimmeridgian, Nerinella Bed. 



Remarks. The specimens are casts preserved in sandstone and retain traces of 

 the concentric ornament of the original shell, although not of any radial ornament 

 that may have been present at its extremities. There is no evidence as to the arrange- 

 ment of the hinge-teeth. The species is referred to Apolinter on account of its very 

 close resemblance to the type-species of that genus, Area aptiensis Pictet & Campiche, 

 as figured by Woods (1899 : 35, pi. 6, figs. 8, 9). The dentition of Apolinter, figured 

 by Casey (1961 : 589, fig. 11a) is of the general type characteristic of the genera 

 Parallelodon and Grammatodon. 



No very closely comparable described Jurassic species can be cited. In the 

 Lower Volgian species " Cucullaea " schourovskii Rouillier, referred to Macrodon by 



