FROM TANGANYIKA AND KENYA 95 



prosogyrous, at about anterior third of length ; inflation weak ; postero-dorsal 

 region compressed, limited in each valve by a strongly curved ridge running from 

 the umbo to the postero-ventral corner. 



Remarks. This lucinid is not referable to any species recorded from the Upper 

 Lias of Europe, but the available specimens are too imperfect to serve as type 

 material of a new species. The species is smaller and less rectangular than Lucina 

 plana Zieten, in which, moreover, there is no compressed postero-dorsal area. The 

 presence of this area also distinguishes it from the Bajocian species L. despecta 

 Phillips, recorded below. 



Lucina despecta Phillips 

 PI. 15, fig. 9 



1829. Lucina despecta Phillips : 150, pi. 9, fig. 8. 



Material. Numerous specimens, all in the form of moulds, on the surface of 

 which traces of the original surface ornament are impressed. 



Localities and horizon. Kidugallo Station and i\ miles E. of Kidugallo 

 Station, Central Railway, Tanganyika ; Bajocian, Station Beds. 



Remarks. The specimens are slightly longer than high, with the umbo broadly 

 rounded, moderately prominent, and placed at about the posterior two-fifths of the 

 length ; the length of a typical specimen is 18-5 mm. The gently sloping postero- 

 dorsal outline forms a well-defined, obtuse angle with the nearly straight and verti- 

 cal posterior margin. The anterior margin is feebly convex and prosocline in its 

 general direction, joining the antero-dorsal margin in a broad curve. The surface is 

 ornamented with concentric ridges which are about 1 mm. apart on the middle of the 

 shell in the best-preserved specimen, with concentric threads in their intervals. Im- 

 pressions of anterior and posterior lateral teeth are preserved. 



Lucina despecta, the holotype of which came from the Inferior Oolite of Yorkshire, 

 has been misinterpreted by many authors and the name has been applied to speci- 

 mens from later geological formations differing considerably from those from the 

 type-horizon. No satisfactory figure of the species, in fact, exists in the literature, 

 the original one of Phillips being a little foreshortened. The East African specimens 

 now recorded have been compared with specimens of L. despecta from Yorkshire, 

 and I can see no reason for separating them specifically from the English species. 

 Lucina paradoxa Waagen (1867 : 621, pi. 31, figs. $a, b), from the Inferior Oolite of 

 Germany, seems very close to L. despecta, although a little more elongate. 



Lucina cf. lirata Phillips 



References to descriptions of the typical L. lirata are as follows : 

 1829. Lucina lirata Phillips : 140, pi. 6, fig. n. 

 1934a. Lucina lirata Phillips ; Arkell : 278, pi. 41, figs. 1-3, 7. 



The form now recorded has been illustrated as follows : 

 i960. Lucina sp. : Joubert, pi. 9, figs. 6a, b. 



