34 BULLETIN 9(3, UNITED STATES NATIONAL MUSEUM. 



Genotype. — Macropova centralis MacGillivray, 1895. 



Range. — Eocene-Recent. Two new species in the American 



Eocene. 



Genus QUADRICELLARIA D'Orbigny, 1850. 



ISW. QuadriceUaria D'Okbigny, Paleontologie francaise, Torraiu cretace, 

 Bryozoaires, vol. 5, p. 32. 



Zoarium articulated; segments quadrangular; two opposite faces 

 with large zocecia and the other two with small zooecia. 



Genotype. — QuadriceUaria elegans D'Orbigny. 



Range. — Turonian-Senonian. Several new species are known in 

 the Early Tertiary of the United States. 



Suborder Ascophora Levinsen, 1909. 



The zooecial hydrostatic system is a sack or compensatrix placed 

 under the frontal and in which the sea water is introduced. The 

 parietal muscles are attached to this sack. 



THE COSTULAE. 



(Family Cribrihnidae Hincks, 1880.) 



The zooecia have their frontal wall formed of flattened ribs ordi- 

 narily hollow, radiating from the outer border toward the median 

 line of the zooecia, where they are intimately joined together; these 

 ribs are united to one another, sometimes by a more or less large 

 number of transverse passages, and sometimes border to border, the 

 ribs, however, always remaining apparent. 



Of the numerous genera referred to this family the following are 

 represented by species in the American Tertiar}^ : 



Menibranipor^lla Smitt, 1873. Cenomanian-Recent. 



Crihrilina Graj^, 1848. Midwayan-Recent. 



Puellina Jullien, 1886. Senonian-Recent. 



Distansescharella D'Orbigny, 1852, Senonian-Jacksonian. 



Gephyrotes Norman, 1903. Jacksonian-Recent. 



Metracolposa^ new genus. Jacksonian. 



Corhulipora MacGillivray, 1895. Eocene, Miocene. 



Acanthocella., new genus. Jacksonian-Recent. 



Crxbrendoecium., new genus. Jacksonian. 



Arachnopima Jullien, 1886. Vicksburgian-Recent. 



METRACOLPOSA, new genus. 



{Metra., womb or ovicell; holpos^ a hollow, referring to the deeply 

 embedded ovicell in the distal zocecia). 



The costules are separated by numerous lacunae. The apertura is 

 semilunar. The operculum in opening closes the ovicell. The ovi- 



