PLATE XL 



PAGE 



Fig. 57. Ostrea Bourqeoisit. Natural size. 33 



57 a. Hinge. 



Fix 58 6. Upper valve of O. Attwoodii? Natural size. 34 



Fig- 59. Ostrea Vkatchii. 34 



From a small and unusually thin specimen. 



Fig. 61. Ostrea Cerrosensis. Natural size. 35 



