FROM TANGANYIKA AND KENYA 125 



meridgian species Corbida vomer Contejean (i860 : 254, pi. 10, figs. 29, 30), but is 

 very much smaller and differs considerably in the direction of its umbonal ridge. 



Corbula kailtaensis sp. nov. 

 PL 19, figs. 13a, b 



Diagnosis. Of medium size for the genus (length of holotype 9-6 mm.), pyriform, 

 height two-thirds of length. Left (and only known) valve gibbose, with a short, 

 narrow posterior rostrum ; umbo broadly rounded, prominent, slightly anterior to 

 mid-length ; antero-dorsal outline very slightly concave, sloping steeply to the 

 broadly rounded anterior extremity of the shell ; ventral margin strongly convex, 

 symmetrical except for a broad, ill-defined sinus at the beginning of the posterior 

 rostrum ; postero-dorsal outline parasigmoidal ; no distinct umbonal ridge. Orna- 

 ment consisting of narrow and slightly unevenly spaced concentric riblets. 



Holotype. No. L. 92036. The only specimen. 



Locality and horizon. Kailta, Golberobe hills, N.E. Kenya ; Oxfordian, 

 Golberobe Beds. 



Remarks. This species rather closely resembles Corbula buckmani Lycett (1863 : 

 63. pL 37. fig- 8), from the Bathonian of England, but in that species there is an obli- 

 que posterior margin which forms an obtuse angle with the hinge-margin, and the 

 narrow posterior rostrum characteristic of the present form is lacking. C. glosensis 

 Zittel & Goubert (figured Chavan 1952, pi. 4, figs. 76-79), from the Upper Oxfordian 

 of Cordebugle, Calvados, France, is not so distinctly rostrate. 



Superfamily PHOLADOMYACEA 



Family PHOLADOMYIDAE Gray 1847 



Genus PHOLADOMYA G. B. Sowerby 1823 



Pholadomya reticulata Agassiz 

 PL 20, fig. 2 



1842. Pholadomya reticulata Agassiz : 80, pi. 4, figs. 4-6 ; pi. 4c, figs. 1-4. 



1874. Pholadomya reticulata Ag. ; Moesch : 28, pi. 9, figs. 2, 4, 5, 9-11. 



1893. Pholadomya reticulata Ag. ; Choffat : 11, pi. 4, figs. 4-7. 



1929. Pholadomya reticulata Ag. ; Lanquine : 203, pi. 7, fig. 8. 



Material. Three specimens (nos. LL. 35076-78). 



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

 Upper Lias, Toarcian, Didimtu Beds. 



Remarks. The largest specimen, the original length of which was slightly more 

 than 25 mm., is much eroded, but the smaller specimen illustrated is ornamented with 

 rather coarse concentric folds crossed by narrow radial riblets which are present on 

 all parts of the shell. There is close agreement with the illustrations cited above. 

 This relatively small Pholadomya was originally described from beds of Upper Liassic 

 age. Its range extends, according to Moesch, into the Bajocian. 



