102 JURASSIC BIVALVIA AND GASTROPODA 



Locality and horizon. Didimtu hill, 2 miles S. of Bur Mayo, N.E. Kenya ; 

 Upper Lias, Toarcian, Didimtu Beds. 



Remarks. This species resembles the European Upper Lias-Bajocian species 

 Protocardia subtrttncata (d'Orbigny) (= Cardium truncatum Goldfuss, 1837 ■ 218, 

 pi. 143, figs, ioa-c, non Phillips) in size and in the general shape of the shell ; it 

 differs, however, in its slightly more prominent umbones, in the absence of a diagonal 

 ridge, in its more rounded posterior margin, and in the presence of granules on the 

 radial riblets on its posterior area. Protocardia ferruginea Rollier ( = P. striatula 

 Benecke 1905 : 228, pi. 17, figs. 1-4, non J. de C. Sowerby), to which the Yorkshire 

 Dogger species erroneously attributed to P. striatula (J. de C. Sowerby) by Phillips 

 (1829, pi. 11, fig. 7) also probably belongs, commonly attains a considerably larger 

 size than that of the present East African specimens, and the riblets on its posterior 

 area are not so conspicuously granose. 



Protocardia besairiei sp. no v. 



PL 16, figs. 8, ga, b, 10 



Specific name. After Monsieur H. Besairie, who collected specimens of the 

 species from Madagascar. 



Diagnosis. Of medium size (length c. 30 mm.), ovate, strongly inequilateral, 

 height about two-thirds of length, beaks from anterior fifth to quarter of length; 

 inflation moderately strong. Umbones broadly rounded, depressed, well incurved 

 to the prosogyrous beaks. Postero-dorsal margin subhorizontal or gently sloping, 

 forming a rounded-off, obtuse angle with more or less oblique, flattened posterior 

 margin ; ventral margin of feeble convexity ; anterior margin strongly convex, 

 anterior end of shell relatively narrow for a Protocardia ; antero-dorsal outline 

 strongly concave. A weak diagonal ridge is present, bordering a rather flattened 

 posterior area. Flank ornamented with somewhat irregular and unequal, rounded 

 concentric ribs. Posterior area with fine radial grooves separating weak riblets. 



Holotype and paratypes. Holotype, no. LL.35128, ex B.P. Coll., the only 

 specimen from East Africa examined. Paratypes, nos. L. 74972-79, from Mada- 

 gascar. 



Localities and horizon. Lihimaliao creek, at a point near Mbaru creek, 

 Mandawa area, Tanganyika (type-locality) ; Bajocian (?), Pindiro Shales. Mont 

 Bovy, Maevatanana, N.W. Madagascar ; Bajocian. 



Remarks. No closely comparable described species can be cited. Obvious 

 differences which distinguish it from P. beneckei Rollier (1912 : 113, 121) (= Proto- 

 cardia sp. ; Benecke, 1905 : 231, pi. 17, figs. 7, 8), from the Lower Bajocian of 

 Lorraine, are its ovate and inequilateral, rather than orbicular, outline, and its 

 rugose, irregularly ornamented flank. 



