138 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



large, porous, shallow, flat, or very little convex; the opesiules are 

 very small lateral slits. The opesium is small, transverse, semi- 

 elliptical. The ovicell is endozooecial, salient, convex, much nar- 

 rower than the zooecium; the opesium of the ovicelled zooecia is 

 much larger than the others. A small triangular transverse avicu- 

 larium surmounts some zooecia; its beak is turned toward the base. 



Measurements . — 



Opesium (or-J^o = 0.07 mm. Opesium (ovi-f/io^O.10 mm. 



dinary) Uo = 0.15 mm. celled) Uo=0.20mm. 



[is = 0.65 mm. 



Zooecium ,. 



\lz= 0.60-0. 70 mm. 



Affinities. — This species differs from Micropora stenostoma Busk, 

 1852, in its much narrower ovicells and in its opesiules of very small 

 slits instead of large pores. It differs from Micropora brevissima 

 Waters, 1904, from the Antarctic in its ovicells of less height and in its 

 opercular dimorphism. It differs from Micropora coriacea Esper, 

 1791, in its large dimensions and its linear opesiules. 



The small opesiules are quite variable and are sometimes reduced 

 to minute pores. 



Occurrence. — D. 5217. Anima Sola Island, between Burias and 

 Luzon; 13° 20' N.; 123° 14' 15" E.; 105 fathoms; crs. gy S.; 17.2° C. 



Eolotype.—C&t. No. 8343, U.S.N.M. 



Genus VIBRACELLA Waters, 1891 



The ovicell is endozooecial. The cryptocyst is developed. The 

 opesium frequently bears lateral opesiular indentations. There are 

 auriform avicularia sporadically intercalated between the zooecia. 

 The colonies are generally free and orbicular. 



Genotype. — Vibracella (Cellepora) trapezoidea Reuss, 1847. 



Range. — Eocene (Lutetian) — Pliocene. 



Following are the known species: 



SOUTHERN HEMISPHERE 



Vibracella grandicella, new species Miocene (Australia). 



Vibracella trifoliata, new species Miocene (Australia) . 



NORTHERN HEMISPHERE 



Vibracella orbicularis Canu, 1907 Lutetian of Paris Basin. 



Vibracella (Selenaria) auriculata Canu and Claibornian of Alabama. 



Bassler, 1923. 

 Vibracella (Pavolunulites) buski Reuss, 1867. Lower Oligocene. 



Vibracella vicksburgica, new species Vicksburgian of Mississippi. 



Vibracella trapezoidea Reuss, 1847 Priabonian, Vicentin, Italy. 



Vibracella miocenica Seguenza, 1877 Tortonian of Italy. 



Vibracella seguenzai Neviani, 1898 Tortonian and Plaisancian of Italy. 



The genus Vibracella differs from Selenaria Busk, 1854, only in the 

 form of the vibracula. Thev are auriform and not ornamented with 



