FROM TANGANYIKA AND KENYA 59 



Genus WEYLA Boehm 1920 



Weyla ambongoensis (Thevenin) 

 PI. 7, figs, ga, b, c 



19086. Pecten ambongoensis Thevenin : 24, pi. 4, figs. 2, 3. 



1948. Pecten ambongoensis Thev. ; Dubar : 220, pi. 29, figs. 7-9. 



Material. Numerous specimens. 



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

 Upper Lias, Toarcian, Didimtu Beds. 



Remarks. The specimens now recorded are quite typical of this species, which 

 is known from the Upper Lias of Pakistan and Morocco as well as from the type- 

 locality in Madagascar. 



Superfamily LIMACEA 



Family LIMIDAE Rafinesque 1815 



Genus LIMA Cuvier 1798 



Subgenus PLAGIOSTOMA J. Sowerby 1814 



Lima (Plagiostoma) biiniensis sp. nov. 

 PL 8, fig. 1 



1929. Cf. Lima (Plagiostoma) cf. rigida Sow. ; Weir : 27, pi. 2, fig. 2. 

 i960. Lima (Plagiostoma) sp. nov. ; Joubert, pi. 8, fig. 4. 



Diagnosis. Of medium size (height of holotype c. 53 mm.), suborbicular, 

 slightly higher than long ; inflation even and moderate. Ventral margin strongly 

 convex and not pronouncedly asymmetrical ; umbonal region obtusely angular in 

 outline, its angle about 100 ° ; anterior umbonal ridge rounded off, relatively short. 

 Main part of surface bearing numerous (probably about 70) radial riblets which 

 project very little, are flat-topped in the holotype, and are separated by much 

 narrower intervals which are seen to be punctate where the shell is least eroded. 

 Auricles not preserved. 



Holotype. No. L. 92174. A few other specimens in the material studied may 

 belong to the same species but are all imperfect and cannot rank as paratypes. 



Localities and horizons. 2 miles W. of Melka Biini, N.E. Kenya ; Bathonian, 

 Murri Limestones. Possible representatives of the species from Kulong, 2 miles 

 S.W. of Muddo Erri, N.E. Kenya ; Callovian [?-Lower Oxfordian], Muddo Erri 

 Limestones. 



Remarks. The ornament of this species much resembles that of the Bajocian 

 species L. semicircularis Goldfuss, discussed by the present writer (Cox 1943 : 160, 

 pi. io, figs. 13, 14). The new species differs, however, in its more even inflation, its 

 shorter and less marked anterior umbonal ridge, and its fewer radial ribs (their 

 number is 80-90 in L. semicircularis). There are many records of L. semicircularis 



