5 o JURASSIC BIVALVIA AND GASTROPODA 



Tendaguru also, it is clear that in East Africa it has a moderately extended geological 

 range. 



Family POSIDONIIDAE 



Genus BOSITRA de Gregorio 1886 



Bositra buchii (Roemer) 

 PI. 6, fig. 1 



1836 

 1851 

 1852 

 1869 

 1896 

 1924 

 1928 

 1930 

 1938 

 1940 



Posidonia Buchii Roemer : 81, pi. 4, fig. 8. 

 Posidonia ornati Quenstedt : 517, pi. 42, fig. 16. 

 Posidonomya alpina Gras : 11, 48, pi. 1, fig. 1. 

 Posidonomya Buchii (Roemer) ; Brauns : 242. 

 Posidonomya Bxichi (Roemer) ; Stremoouchow : 391, pi. 10. 

 Posidonomya Buchii (Roemer) ; Hennig : 43. 

 Posidonomya alpina Gras ; Guillaume : 228, pi. 10, figs. 4-13. 

 Posidonia ornati Quenstedt ; Weir : 83, pi. io, figs. 14-21. 

 Posidonia ornati Quenstedt ; Weir : 45, pi. 3, fig. 5. 

 Posidonia ornati Quenstedt ; Cox : 103, pi. 7, figs. 10, n. 



Material. Numerous specimens. 



Localities and horizons. Kidugallo Station, Central Railway, Tanganyika ; 

 Bajocian, Station Beds. Boreholes 5 miles N. of Kidugallo and at Lugoba, Tangan- 

 yika ; Lower Bajocian (Aalenian) (see Arkell, 1956 : 330). About 2.\ miles S.S.W. of 

 Tengeni (village on Pangani river), N.E. Tanganyika ; horizon uncertain. Kaya 

 Kauma, 8 miles W. of Kilifi, Kenya ; Upper Callovian, Miritini Shales. 



Remarks. Many authorities have recognized that Posidonia buchii was founded 

 on an unusually elongate specimen of the species more commonly known as P. ornati 

 Quenstedt or as P. alpina (Gras) , and this view is here accepted, although in previous 

 works I have used Quenstedt's name for the species. It has an exceptionally long 

 geological range, extending from the Toarcian (in Argentina) to the Upper Callovian. 

 The recent work of R. P. S. Jefferies has shown that there are good grounds for the 

 generic separation of P. buchii and related Jurassic forms from the type-species of 

 Posidonia, P. becheri Bronn of the Carboniferous, and the generic name Bositra has 

 long been available for them. 



Bositra somaliensis (Cox) 

 PI. 6, fig. 2 

 1935a. Posidonia somaliensis Cox : 166, pi. 15, figs. 7, 8. 



Material. One specimen (no. L. 51207). 



Locality and horizon. Kindope valley, N.N.W. of Tendaguru, Tanganyika ; 

 Upper Kimmeridgian, Nerinella Bed. 



Remarks. This valve of a Bositra, which is about 20-5 mm. long and slightly less 

 in height, seems referable to B. somaliensis in view of its size and known geological 

 age. B. bononiensis (de Loriol) (1875 : 170, pi. 21, figs. 3-5), from the Kimmeridgian 

 of France, is a much smaller form. 



