298 Mayer-Eymar, Diagnoses Ostrearum novarum 



culi subtriangulari, leviter obliqua; valva superiore minore, 

 plano-convexa, leviter lamellosa; cardine lato, piano; mar- 

 ginibus superne creniilatis, inferne leviter denticulatis. 



Londinianum I: El Guss Abu Said (4) etXokba(3), 

 oasis Farafrali. Mus. Mon. 



Londinianum II: Mons Medine Abu prope Theben. 

 (3) Mus. Tur. 



Parisianum I, a: Mokattam. (1) Mus. Tur. 



Ostrea sororcula, May.-Eym. 



0. testa parvula, irregulariter ovato-rotundata, leviter 

 obliqua, solidula; valva inferiore paulum convexa, plerum- 

 que umbone adnata; costis satis nummerosis, intersticiis 

 aequalibus vel latioribus, fornicatulis, a striis concentricis 

 tenuissimis lamellisque paucis decussatis; umbone parvo, 

 saepe acutiusculo; cardine latiusculo, canali profundius- 

 culo, areas subaequante; marginibus superne intus scro- 

 biculato-striatis; cicatricula musculi subtriangulari, leviter 

 obliqua; valva superiore minore, plano-convexa, leviter 

 lamellosa. — Long. 18, lat. 18 millim. 



Londinianum I: El Guss Abu Said. (3) Mus. Mon. 



E Serie Ostreae punctatae. 



Ostrea tihana, May.-Eym. 



0. testa parva, ovato-angusta, recta, compressa; 

 valva inferiore solidula, dorso toto adnata, lateribus co- 

 stellata; costellis numerosis, filiformibus, aequalibus, saepe 

 dichotomis, irregulariter sulcato-subgranosis; umbone re- 

 curvo, obtuso; latere antico longo, subrecto; cardine in- 

 curvo, canali angusto, profundo, areis lamellaribus ; mar- 

 ginibus superne profunde scrobiculatis, fere ex toto den- 

 ticulatis; cicatricula musculi laterali, ovato-triangulari, 

 leviter obliqua; valva superiore minore, convexiuscula, 

 saepe dorsata, irregulariter tenuilamellosa; umbone an- 



