464 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Genus ICHTHYARIA Busk, 1884 



The zoarium is unilamellar and biserial. There are apertural 

 septulae. The ovicell is not closed by the operculum. 



Genotype. — Ichthyaria oculata Busk, 1884. Recent. 



There is no ascopore shown on the figures of Busk, 1884, or of 

 Waters, 1889, but there is one on the figure of Harmer, 1902. 



Family EUTHYRIDAE Levinsen, 1909 



The zooecia are slightly calcified, and in a larger or smaller part of 

 their surface the surrounding ectocyst is kept distended by ridge-like 

 or rod-shaped processes from the sub-adjacent olocyst which has a 

 number of superficial septulae. The interzooecial walls have scat- 

 tered uniporous septulae. The operculum is compound. The ovicell 

 is wanting or endozooecial. The zoarium is free, branched, flexible 

 (after Levinsen). 



Genus URCEOLIPORA MacGillivray, 1881 



The ovicell is endozooecial. The apertura is provided with a 

 narrow sinus. The ectocyst is everywhere kept distended by narrow 

 ridges from the olocyst (after Levinsen). 



Genotype. — Urceolipora nana MacGillivray, 1881. Recent (Aus- 

 tralia). 



Genus EUTHYRIS Hincks, 1882 



No ovicell, but two different forms of zooecia. The aperture has 

 two cardelles. The frontal forms a continuous calcareous surface. 

 The ectocyst is on the frontal as well as on the basal surface dis- 

 tended by means of rod-shaped processes from the olocyst. (After 

 Levinsen, 1909.) 



Genotype. — Euthyris ootecta Hincks, 1882. Recent (Australia). 



Genus PLEUROTOICHUS Levinsen, 1909 



No ovicell, but two different forms of zooecia. The apertura has 

 two cardelles. The frontal is formed by a number of narrow, only 

 partially meeting, ribs; the ectocyst is distended only on the basal 

 surface of the colony by means of the wedge-shaped, projecting, 

 central portion of the separate zooecia (after Levinsen). 



Genotype. — Pleurotoichus (Eathyris) clathratus Harmer, 1902. Re- 

 cent (Australia). 



