FROM TANGANYIKA AND KENYA 79 



Material. Very numerous specimens. 



Localities and horizon. Many localities around Tendaguru, Tanganyika ; 

 Upper Kimmeridgian. 



Remarks. The trigoniids of the T. smeei group occurring in Tanganyika have 

 recently been treated exhaustively by Aitken (1961), who considers that they belong 

 to at least five species, none identical with the true T. smeei, which occurs in the 

 Upper Oxfordian of Cutch, India. The name T. (Indotrigonia) africana is assigned 

 by him (1961 : 75, pi. 8, figs. 2-7 ; pi. 9, figs. 1, 2) to the form most commonly found 

 at Tendaguru. 



Trigonia {Indotrigonia) dietrichi Lange 



1914. Trigonia dietrichi Lange : 233, pi. 20, fig. 7. 



1933. Trigonia (Indotrigonia) dietrichi Lange ; Dietrich : 32, pi. 2, figs. 38-41. 



Material. Two specimens (nos. L. 52640, L. 52664). 



Locality and horizon. Kindope valley, near Tendaguru, Tanganyika ; Upper 

 Kimmeridgian, " Trigonia smeei " Bed. 



Remarks. These specimens, which are imperfect, agree with T. dietrichi as 

 figured by Dietrich, and show the strong upward bend of the costae as they approach 

 the marginal carina. This is not a feature indicated in Lange's original figure, but 

 his description refers to a slight upward bend of the costae. 



Genus MYOPHORELLA Bayle 1878 



Myophorella quennelli sp. nov. 

 PI. 12, figs, la, b 



Specific name. After Mr. A. M. Quennell, formerly Director of the Tanganyika 

 Geological Survey, collector of the type specimens. 



Diagnosis. Of small-medium size (original length of paratype, the larger speci- 

 men, c. 30 mm.), length only slightly in excess of height ; umbo moderately pro- 

 minent ; anterior and ventral margins forming a broad curve. Marginal carina 

 strongly curved ; posterior area broad, forming a wide angle with the flank, and with 

 an almost vertical posterior margin. Flank ornamented with feebly curved, weakly 

 tuberculate costae which extend to the marginal carina and slope steeply down from 

 it except in the earlier growth-stages, where they are concentric about the umbo. 

 The intervals are about twice the width of the costae except in the posterior corner of 

 the flank, where they are narrower. Two short costae, seen in the holotype but 

 obscured in the paratype, occupy the space near the anterior margin corresponding 

 to the change in the curvature of the main costae. Area without sulcus or radial 

 ribs, but crossed by closely and evenly arranged ridges parallel with posterior 

 margin. 



Holotype and paratype. Holotype, no. LL.11809 ; one paratype, no. LL.11810. 

 Both are left valves. 



