68 JURASSIC BIVALVIA AND GASTROPODA 



and, apparently, more lamellose plications than the shell now recorded ; it most 

 probably also belongs to L. costata. 



Lopha olimvallata nom. nov. 



PL 9, figs. 2a, b 



1874. Ostrea vallata Dumortier : 203, pi. 45, figs. 7, 8 (non Thurmann & Etallon, 1862). 



1905. ? Ostrea sp. ; Benecke : 161, pi. 12, fig. 12. 



1929. Alectryonia vallata Dumortier ; Schafle : 64, pi. 6, figs. 6-8. 



1935. Alectryonia vallata Dumortier ; Kuhn : 119, pi. 8, fig. 30. 



Material. One specimen (no. LL. 35026). 



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

 Upper Lias, Toarcian, Didimtu Beds. 



Description. This specimen is an elongated, linguiform, shallow left valve 51 

 mm. high and 20 mm. broad, attached by almost its entire surface to a lamina of 

 fibrous calcite, to the other side of which some smaller and less complete right valves 

 are attached. The low sides of the valve rise steeply from the attachment area and 

 have a number of rather weak, irregular plications. The umbo is directed in an 

 anterior direction to a slight extent. 



Remarks. In the type-specimen of Ostrea vallata, which came from the Upper 

 Lias of southern France, and in specimens from the Upper Lias of Germany figured 

 by Schafle, the height of the shell is only slightly in excess of the breadth. In the 

 shell from the Aalenian of Lorraine figured by Benecke as " Ostrea sp. ", and con- 

 sidered by Schafle to belong to Dumortier's species, the shape is narrow and lingui- 

 form and the umbo is directed anteriorly exactly as in the specimen now recorded, 

 although the plications of the shallow sides of the valve are stronger and more 

 numerous. The present specimen is thought to be referable to Dumortier's species 

 as interpreted by Schafle and now renamed. 



Lopha gregarea (J. Sowerby) 

 PI- 9. ng. 5 



1815a. Ostrea gregarea J. Sowerby : 19, pi. 111, figs. 1, 3. 



1933a. Lopha gregarea (Sowerby) ; Arkell : 183, pi. 22, figs. 5, 6 ; pi. 23, figs. 1-4. 



1952. Lopha gregarea (Sowerby) ; Cox : 96, pi. 4, fig. 2 ; pi. 10, figs. 7-13. 



i960. Lopha gregarea (Sowerby) ; Joubert, pi. 9, fig. 1. 



Material. Several specimens. 



Localities and horizons. 3! miles W. of Melka Biini ; also hills S. of Rahmu- 

 Melka Murri road, 11 miles and 13 miles W. of Rahmu, N.E. Kenya ; Callovian, 

 Rukesa Shales. S. of Rahmu-Melka Murri road, 6 miles W. of Rahmu, N.E. 

 Kenya ; Callovian [?-Lower Oxfordian], Muddo Erri Limestones, if miles S.W. of 

 Rahmu and 6| miles S.S.W. of Rahmu, N.E. Kenya ; Oxfordian, Rahmu Shales. 

 Wilderri hill, 11 miles S.S.W. of Rahmu, N.E. Kenya ; Upper Oxfordian, Seir 



