FROM TANGANYIKA AND KENYA 123 



strongly convex ; antero-dorsal outline slightly concave ; a sharply angular, 

 sigmoidal diagonal ridge delimits a narrow, concave posterior area. Ornament of 

 strong, unequal, unevenly arranged concentric riblets and threads on flank, and finer 

 growth threads on posterior area. 



Holotype and paratypes. Holotype, no. LL.35152 ; about 16 paratypes, in- 

 cluding no. LL. 35153, and mostly very imperfect. All ex B.P. Coll. 



Locality and horizons. Pindiro well no. i, Tanganyika, at depths 162-166 feet, 

 166-170 feet (holotype), 170-174 feet, 174-178 feet, 178-180 feet, 194-198 feet, 

 250-254 feet ; Bajocian (?). 



Remarks. This species does not closely resemble any corbulid previously 

 described from the Middle Jurassic. The English Bathonian form C. attenuata 

 Lycett (1863 : 62, pi. 37, figs. 6, 6a) is more elongate, with a broader and less prom- 

 inent umbo. 



Corbula kidugalloensis sp. nov. 

 PI. 19, figs. 17a, b, c 



Diagnosis. Of medium size for the genus (length of holotype 1 1 -2 mm.) , pyriform, 

 with a short posterior rostrum, subequivalve, gibbose ; height equal to about three- 

 quarters of length. Umbones broadly rounded, prominent, almost median in 

 position, well incurved to the prosogyrous beaks. Lunular region well impressed. 

 Antero-dorsal outline slightly concave, sloping steeply to the evenly rounded anterior 

 end of the shell. Ventral margin asymmetrically and rather strongly convex, with 

 a small sinus (indicated by the growth-lines, this part of the actual margin being a 

 little imperfect) at the beginning of the pointed rostrum. Postero-dorsal outline 

 almost straight, sloping steeply ; posterior umbonal ridges weak, sigmoidally curved. 

 Ornament consisting in early stages of growth of regularly arranged, narrow concentric 

 riblets, separated by broader intervals ; in later growth-stages these are replaced by 

 irregular rugae. 



Holotype. No. LL. 35154, ex B.P. Coll. The only specimen. 



Locality and horizon. Magole, 5 miles N.W. of Kidugallo, Tanganyika ; 

 Bajocian. 



Remarks. Its much larger size distinguishes this species from Corbula tangany- 

 icensis sp. nov., which is very similar in shape. 



Corbula earnest sp. nov. 

 PI. 19, figs. 19a, b, c 



Specific name. After Dr. F. E. Eames, Chief Palaeontologist of the British 

 Petroleum Co., Ltd. 



Diagnosis. Of large-medium size for the genus, pyriform but not distinctly- 

 rostrate posteriorly, length (16 mm.) exceeding one and a half times the height 

 (which may, however, have been somewhat reduced by distortion) ; fairly strongly 



