FROM TANGANYIKA AND KENYA 25 



already discussed and, limited though this evidence is, it favours the inclusion of 

 the Danissa Beds, like the Mandera Series below them, in the Jurassic. 



IV SYSTEMATIC DESCRIPTIONS 



Class BIVALVIA Linnaeus 

 Superfamily NUCULACEA 

 Family CTENODONTIDAE Wohrmann 1893 

 Genus PALAEONEILO Hall 1869 



Palaeoneilo asaharbitensis sp. nov. 

 PI. 1, fig. 1 



Diagnosis. Of medium size for the genus (length of holotype 20 mm.), sub- 

 elliptical, height about three-fifths of length ; moderately inequilateral, with the 

 umbo near the anterior third of the length ; inflation rather strong for the genus. 

 Umbo narrowly rounded, its outline continuous with the almost straight, gently 

 sloping postero-dorsal outline of the shell ; antero-dorsal outline strongly excava- 

 ted. Anterior margin broadly rounded, posterior margin more narrowly rounded, 

 ventral margin strongly and nearly symmetrically convex. Details of ornament 

 unknown. 



Holotype. No. L. 83864, the internal mould of a left valve. The only specimen. 



Locality and horizon, i mile N. of Asaharbito, N.E. Kenya ; Bathonian 

 [? or Callovian], Asaharbito Beds. 



Remarks. The muscle scars and pallial line are not seen in the holotype, and 

 impressions of taxodont teeth, while clearly visible along the postero-dorsal and 

 antero-dorsal margins, are obscured immediately below the umbo. Hence the 

 reference of the species to the genus Palaeoneilo is based on its general morphology. 

 The most closely comparable form described from the Middle or Upper Jurassic is 

 P. longiuscula (de Loriol) (1899 : 159, pi. 10, figs. 23-25, ex Merian MS.), Lower 

 Oxfordian of Switzerland, which is slightly more elongate. 



Family NUCULIDAE 



Genus NUCULOMA Cossmann 1907 



Subgenus PALAEONUCULA W. Quenstedt 1930 



Nuculoma (Palaeonucula) bellozanensis (de Loriol) 

 PI. 1, figs. 3a, b 



1875. Nucula bellozanensis de Loriol : 138, pi. 17, figs. i6a-c. 

 Material. One specimen (no. L.92293). 



