14 PKOCEEDINGS OF THE NATIONAL MUSEUM vol.72 



SYSTEMATIC DESCRIPTIONS 



Order CHEILOSTOMATA Busk 

 Suborder Anasca Levinsen 



Division MALACOSTEGA Levinsen, 1909 

 Family BIFLUSTRIDAE Smitt, 1872 



Membraniporae without ovicells. The zooecia are rectangular 

 (seen on their dorsal face) . No spines. 



In this family we classify all the genera of the first group of 

 Membraniporae as we divided them in 1920 (p. 85). 



History. — Bijiustra is a zoarial genus established by D'Orbigny, 

 1852, and classed in his family of Flustrellariidae. It embraced all 

 of the bilamellar Membranipores. Three recent species were classed 

 here — the first and the third are of the Savartii group (Waters, 1905) 

 and the second is one of the Costulae. Busk, 1859, classed Bijiustra 

 in the Escharidae; he introduced here Bijiustra delicatula, which we 

 know to be a synonym of Flustra savartii Savigny-Audouin, 1826. 



Smitt, 1872, formed the family of Biflustridae for the reception of 

 the genus Bijiustra. "The quadrangular shape of the zooecia, as 

 well as their strong, usually high, and hardly calcified and granular 

 margins, in most cases will make the biflustridan type recognizable." 

 He cites three species: Flustra lacroixii Savigny-Audouin, 1826, 

 although under this name he figures Oallopora Jilum JuUien, 1902; 

 Bijiustra denticulata, which is of very different structure {Hemisep- 

 tella); and Flustra savartii Savigny-Audouin, 1826. 



As Bijiustra has had no definite standing and as the paleontologists 

 have described under that name a great number of species of very 

 different structure, we created in 1917 the genus Acanthodesia for 

 Flicstra, savartii in order to avoid all confusion. Bijiustra is retained 

 for narrow bifoliate Membranipores of doubtful affinities, but we can 

 maintain Smitt's name for the family. In the absence of known 

 larvae, we can not say if this family is a natural one. 



Genus ACANTHODESIA Canu and Bassler, 1920 



ACANTHODESIA SAVAETI Savigny-Audouin, 1826 



Plate 1, Figures 5, 6; text Figure 1. 



1920. Acanthodesia savarti Canu and Bassler, North American Early 

 Tertiary Bryozoa. Bull. 106, U. S. National Museum, p. 100, 

 pi. 21, figs. 2-4. (Bibliography and distribution.) 



1923. Acanthodesia savarti Canu and Bassler, North American Later 

 Tertiary and Quaternary Bryozoa. Bull, 125, U. S. National 

 Museum, p. 31. (Study of the varieties.) 



