■jo J I RASSIC BIVALVIA AND GASTROPODA 



Material. Several specimens. 



Localities and horizons, if miles S.W. of Rahmu, N.E. Kenya, and river 

 section W. of Rahmu-El Wak road, 5^ miles S.W. of Rahmu ; Oxfordian, Rahmu 

 Shales. Golberobe hills, N.E. Kenya ; Oxfordian, Golberobe Beds. Dusse, i\ 

 miles S.E. of Rahmu, N.E. Kenya, and Wilderri hill, 11 miles S.S.W. of Rahmu ; 

 Upper Oxfordian, Seir Limestones. Chamgamwe, near Mombasa, Kenya ; Kim- 

 meridgian, Chamgamye Shales. 



Lopha tifoensis sp. nov. 

 PI. 10, figs. 1, 2, 6, 7 



1957. Lopha sp. ; Saggerson & Miller : 20, fig. e. 



Diagnosis. Shell small (height of largest specimen 27 mm.), trigonal to ovate, 

 variable in proportions but usually higher than long, with deep but relatively thin- 

 shelled lower valve and flat upper valve. Attachment-area conspicuous, fairly large 

 in some specimens, terminal, truncating the umbonal region. Surface of lower valve 

 with a series of irregularly distributed, rounded costae, some fading away during 

 growth while others appear by intercalation and bifurcation, diverging to margins 

 from points close to attachment-area. Where they first appear the number of 

 costae is about 4-6 ; in the holotype, a specimen 14 mm. high, and in the largest 

 paratype, mentioned above, the number of costae reaching the margin is about 10, 

 but in another specimen, 18 mm. high, the number is 16. Upper valve with de- 

 pressed, rounded radial costae originating at same stage of growth as in lower valve. 



Holotype and paratypes. Holotype, no. L. 93574 ; several paratypes, of 

 which L. 93561, L. 93563 and L. 93580 are figured. 



Localities and horizon. Tifo (type-locality), Korkai Hammassa, Ogar Wein, 

 Chimpa, and Asahaba, all N.E. Kenya ; Oxfordian, Golberobe Beds. 



Remarks. While in most specimens the height considerably exceeds the length, 

 the specimen represented in fig. 2 is remarkable for its quadrate outline. Its 

 attachment-area is unusually large and its ribs very weak. Some specimens of this 

 species were originally identified as Lopha costata (J. de C. Sowerby), to which it 

 appears to be closely related. It differs from Sowerby's species, however, in its much 

 more depressed and rounded costae. 



Lopha ? kindopeensis sp. nov. 

 PI. 10, figs. 3, 4a, b, 5 



Diagnosis. Moderately large (height of holotype 96 mm.), trapezoidal, typically 

 with more or less straight anterior and posterior margins diverging from the base of 

 a broad ligamental area, and tending to be subangular postero-ventrally. Both 

 valves fairly thick-shelled and almost flat, differing very little in convexity. (The 

 left valve, however, is known only by imperfect specimens mostly growing attached 

 to the greater part of the surface of right valves, the exteriors of which are thus 



