64 JURASSIC BIVALVIA AND GASTROPODA 



Remarks. This shell is much narrower than L. kindopeensis sp. nov., described 

 above, and also differs in the absence of a distinct anterior umbonal ridge and lunule 

 and of distinct radial ribs except on the anterior part of the surface. 



Genus PSEUDOLIMEA Arkell 1932 



Pseudolimea duplicata (J. de C. Sowerby) 

 PI. 8, figs. 8a, b 



1827a. Plagiostoma duplicata J. de C. Sowerby : 114, pi. 559, fig. 3. 



1932a. Lima (Pseudolimea) alternicosta Buvignier ; Arkell : 140, pi. 13, figs. 3-5. 



1933. Lima (Radula) sp. ; Dietrich : 63, pi. 7, figs. 96-98. 



1944a. Pseudolimea duplicata (Sow.) ; Cox : 84. 



1952. Pseudolimea duplicata (Sow.) ; Cox : 60, pi. 5, figs. 11, 12. 



Material. Several specimens. 



Localities and horizons. Kulong, 2 miles S.W. of Muddo Erri, N.E. Kenya ; 

 Callovian [?-Lower Oxfordian], Muddo Erri Limestones. Dusse, i| miles S.E. of 

 Rahmu, N.E. Kenya ; Upper Oxfordian, Seir Limestones. Kindope, N.N.W. of 

 Tendaguru, Tanganyika ; Upper Kimmeridgian, Nerinella Bed. 



Remarks. The Pseudolimea which occurs in some abundance at Tendaguru and 

 was recorded as Lima [Radula) sp. by Dietrich does not appear to be distinguishable 

 specifically from the long-ranging species P. duplicata, the synonymy of which is 

 given in my two papers cited above. The largest Tendaguru specimens are, indeed, 

 only 13 mm. high and thus smaller than specimens from many localities, but the 

 general proportions of the shell, the number of ribs (22) and their V-shaped cross- 

 section, and the presence of a radial thread in each interval are exactly as in P. 

 duplicata. The specimens from lower horizons in northern Kenya are in every way 

 typical. The known range of the species in Europe is from Toarcian to Upper 

 Oxfordian, with an unconfirmed record from the Portlandian. 



Pseudolimea mandawaensis sp. nov. 

 PI. 8, fig. 3 



Diagnosis. Large for a Pseudolimea, broadly trapeziform, length and height 

 about equal (c. 40 mm.), ventral margin strongly asymmetrical, umbonal region 

 slightly obtuse. Postero-dorsal region only slightly impressed ; auricles unknown. 

 Main ribs about 23, obtusely angular, depressed, with broadly rounded, slightly un- 

 equal intervals bearing numerous fine, unevenly spaced radial threads with one near 

 middle slightly more prominent than the others ; in addition, a few weak, jagged radial 

 riblets occupy anterior and posterior ends of shell. Concentric ornament, except 

 near ventral margin, consisting of closely and evenly spaced threads which are even 

 more delicate than the radials ; late growth stages, however, are marked by irregular 

 concentric rugae. 



