PLATE IV. 



Fig. 



1. Estheria elliptica (p. 103). Right valve; Obernkirchn, Hanover: X 6 diam. 



2. „ „ Right valve of a smaller individual, subquadrate or ovate- 



oblong : X 6 diam. 



3. „ „ Right valve of a suborbicular individual : x 6 diam. 



4. 5. „ ,, Portions of the surface of fig. I: X 50 diam. 



6. „ ,, Left valve of small individual, ovate-oblong or subquad- 



rate, with distinct ridges -. X 6 diam. 



7. ,, ,, Portion of the surface of the same, taken from near the 



ventral edge: X 100 diam. 



8. Estheria Forbesii (p. 109). — Right valve; Cacheuta, South America: X 6 diam. 



9. „ „ [Within the outline of E. Middendorfii?\ A smaller 



suborbicular specimen : X 6 diam. 



10. „ „ A still smaller individual : X 6 diam. 



11. „ „ Portion of the surface of fig. 8 : X 50 diam. 



12. Estheria Middendorfi (p. 111). — Outline of the left valve ; Tourga, Siberia: nat. size. 



13. „ „ Outline of the same : X 6 diam. 



14. ,, „ Natural cast, in shale, a portion of the surface : 



X 50 diam. 



15. ,, ., The surface- ornament restored from the cast, 



fig. 14 : X 50 diam. 



16. „ „ Portion of the surface, including parts of two 



interspaces, one of which is partly occupied 

 by the real carapace, the other being almost 

 all a cast or impression in shale ; the 

 globular bodies and casts are referable to 

 ova : X 50 diam. 



17,18.,, „ Natural casts or impressions of portions of the 



carapace; fig. 17 corresponding to such a 

 portion as the lower part of fig. 16 : X 50 

 diam. 



19. ,, „ Portion of the reticulated surface : X 80 diam. 



20 — 22. „ Some of the oviform bodies : X 80 diam. 



