FROM TANGANYIKA AND KENYA 43 



Remarks. Although ill-preserved, these specimens can be seen to have the strong 

 inflation and the general outline of Newton's species, the holotype of which, from 

 the Bathonian of Madagascar, is in the British Museum (Natural History). Hennig 

 (1914a : 65 ; 1924 : 31) has already recorded the presence of a form identified as 

 Gervillia aff. iraonensis in Tanganyika. 



Genus GERVILLELLA Waagen 1907 



Gervillella didimtuensis sp. nov. 

 PI. 4, figs. 5rt, b, 6 



Diagnosis. Of medium size (measuring up to 50 mm. from anterior end of 

 hinge-line to extremity of body), moderately inflated, trapezoidal, oblique ; shell- 

 wall very thick. Anterior and ventral margins forming a strongly convex, uninter- 

 rupted curve. Body of shell broad, evenly inflated, its level descending gradually 

 to the anterior margin and to the posterior wing. Length of hinge-margin about 

 four-fifths of that of shell ; posterior wing obtusely angular, apparently not acutely 

 pointed at its tip in any stage of growth. Anterior auricle absent ; beak terminal 

 in most specimens, but in some the anterior margin projects very slightly beyond it. 

 Umbo projecting only very slightly above hinge-margin. Ligamental pits four or 

 fewer, extending from beak along about two-thirds of hinge-margin. A rather long, 

 oblique, ridge-like tooth, inclined at an angle of about 45 ° with the hinge-margin, 

 originates just below the beak ; posterior to it are several small, similarly oblique 

 teeth, and near the posterior end of the hinge-margin and diverging only slightly 

 from it is a strong, elongate tooth. 



Holotype and paratypes. Nos. LL. 35012 and LL. 35013-16 respectively, five 

 specimens in all. 



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

 Upper Lias, Toarcian, Didimtu Beds. 



Remarks. The absence of an anterior auricle readily distinguishes this species 

 from the Bajocian form, Gervillella orientalis, described next. 



Gervillella orientalis (Douville) 

 PL 4, figs. ja, b, 8 



1916. Gervillia orientalis Douville : 59, pi. 4, figs. 14-17. 



Material. Several specimens ; ex B.P. Coll. 



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

 Mandawa area, Tanganyika ; near site of Mandawa well no. 1, Tanganyika ; depth 

 50-52 feet in Mandawa well no. 6, Tanganyika ; all Bajocian (?), Pindiro Shales. 



Description. The shell is of medium size (measuring up to 40 mm. from tip of 

 anterior auricle to extremity of body), subequivalve, oblique. The length of the 



