VOL. XVII. (2) JURASSIC GERVILLI^ 253 



EXPLANATION OF PLATE XXVIIL 



Figs. la-d. — Gervillia crassa J. Buckman 



irt = right valve of lectotype ; ib = left valve of lectotype ; 

 ic = left valve of syntype ; id = right valve of syntype. 

 Horizon : Lower Lias (? top of Sinemurian). 



Locality : " Railway cutting .... between Gloucester and Breclon." 

 Collection : Mus. Pract. GeoL, Jermyn Street, London. [Reg. Nos. 3684 

 (lectotype) and 25177 (syntype)]. 



Figs. 2a and 26. — Gervillia l^vis J. Buckman 



2a = right valve of holotype ; 26 = left valve of holotype. 



Hor. : Striatum-'Beds of the Lower Lias, Pliensbachian. 



Loc. : Battledown, Cheltenham. 



Colin. : Mus. Pract. GeoL, Jermyn Street, London. [Reg. No. 3683]. 



Fig. 3. — Gervillia fornicata Lycett 



Left valve of idiotype. 



Hor. : Upper Lias. Toarcian. 



Loc. : Nailsworth, Gloucestershire. 



Colin. : Mus. Pract. GeoL, Jermyn Street, London. [Reg. No. 25183]. 



Figs. 4a-c. — Gervillia lata Phillips 



4a == right valve of lectotype ; 46 = left valve of lectotype ; 



4c = dorsal view of lectotype. 



Hor. : Dogger (Inferior Oolite). Aalenian. 



Loc. : " Blue Wick [Ravenscar, Yorkshire]." 



Colin. : The Museum, York. 



[All the figures are about natural size). 



