408 MAYER-EYMAR. — DIAGNOShS D'HUITRES NOUVELLES 3o 



umbone parvo, sjepe acutiusculo; cardine latiusculo, canali profun- 

 diusculo, areas suhaequante; marginibus superne intus scrobiculato- 

 striatis; cicatricula musculi subtriangulari, leviter obliqua; valva 

 superiore minore, plano-convexa, leviter lamellosa. — Long. 18, ïat. 

 1,8 mili. 



Londinien inférieur d'El Guss Abou Said (3) — M. 

 Groupe de YOsirea punctata. 

 Ostrea tihana, May-Eym. 



O. testa parva, ovato-angusta, recta, compressa; valva inferiore 

 solidula, dorso toto adnata, lateribus costellata ; costellis numerosis, 

 filiformibus, aqualibus, saepe dichotomis, irregulariler sulcato-subgra- 

 nosis; umbone recurvo, obtuso; latere antico longo subrecto ; cardine 

 incurvo, canali angusto, profundo, areis lamellaribus ; marginibus 

 superne profunde scrobiculatis, fere ex toto denticulatis ; cicatricula 

 musculi laterali, ovato-triangulari, leviter obliqua; valva superiore 

 minore, convexiuscula, saepe dorsata, irregularitér tenuilamellosa ; 

 umbone angustato, plcrumque truncatulo ; cardine piano; marginibus 

 ex toto crenatis, — Long. 22, lat. 12 millim. 



Parisien supérieur (II, b) du Wadi elTih. (3) — Z. 



