186 BtTTT.F.Tiy 125, UNITED STATES NATIONAL MUSEUM. 



So far as known this family is not represented in the American Tertiary, but 

 its species, on the contrary, are of common occurrence ui the Miocene and Pliocene 

 of Europe. The larva in all of these genera is unknowTi and their classification 

 necessarily remains doubtful. 



Genus MYRIOZOUM Donati, 1750. 

 1750. Myriozoum Donati, Stagie della storia naturale dell' Adriatico. W 

 The zoarium is free, cylindrical, and arborescent. Septulae are present. 

 Sixteen tentacles. 



Genotype. — Myriozoum (Millepora) truncatum T alias, 1766. 

 Range. — Helvetian-Recent. 



Genus MYRIOZOELLA Levinsen, 1909. 

 1909. Myriozoella Levinsen, Morphological and Systematic Studies on the Cheilostomatous Bryozoa, 

 p. 297. 



The zoarium is incrusting. Dietellae are present. Fifteen tentacles. 

 Genotype. — Myriozoella (Myriozoum) Crustacea Smitt, 1868. Recent. 



ORBITULIPORIDAE, new family. 



The zooecia are regularly arranged vertically; the gemmation is lateral. The 

 apertura is terminal. The ovicell is hyperstomial and forms a tube placed in a 

 zooecium larger than usual. 



The genera of this family are as follows : 



Orhitulipora Stoliczka, 1861. 



Stichoporina Stoliczka, 1861. 



Batopora Reuss, 1867. 



Mamillopora Smitt, 1872. 



Sphaerophora Haswell, 1880. 



Fedora Jullien, 1882. 



Schizorthosecos Canu and Bassler, 1917. 



f Diplotaxis Reuss, 1867. 



Affinities. — This new family differs from the Conescharellinidae Levinsen, 

 1909, in the constant presence of an ovicell. It differs from the Myriozoidae in 

 having the oviceU adjacent to a zooecium. 



Historical. — In 1917 we included the genera of this new family with the Cone- 

 scharellinidae Levinsen, 1909, but after a careful studj' of this latter family based 

 upon specimens from the Philippine Islands we believe that the analogy between 

 them is purely zoarial and that they must be separated. Their system of incuba- 

 tion is totally different, indicating that their larval system is also very different. 



In 1885 Koschinsky discovered in the Bavarian Lutetian a series of forms 

 which he classed in Stichoporina Stoliczka, 1881. This error has been repeated by 

 Waters, Kirkpatrick, Neviani, and Canu. Calvet alone, in 1907, compared Sticho- 

 porina of authors with Mamillopora Smitt, 1872. In 1919 Waters established the 

 truth of this observation by a study of some excellent specimens and classified the 

 principal genera as follows: 



A. With a pit: Batopora, Orhitulipora, Sphaerophora, Stichoporina. 



B. Without a pit: Mamillopora, Conescharellina. 



