NORTH AMERICAN EARLY TERTIARY- BRYOZOA. 



703 



ERKOSONEA, new genus. 



Greek: erkos, partition in allusion to the ornamentation of the dorsal. 



The zoarium is idmoneiform. The dorsal bears dactylethrae, which appear 

 also on the frontal at the bifurcations. The ovicell is globular, spread out between 

 three fascicles over the width of the zoarium. 



D x25 



FIG. 250. Mcsonea, new genus. 



A-G. Mcsnncd. (Rctcpora) radiim/i Lamarck, 1816. A. Ovicellecl zoarinui. .interior face. 

 (After MacGillivray, 1880.) B. Ovicell, X 25, seen in profile and showing the porous windows. 

 C. Transverse section of the ovicell, X 85. (After Waters, 1887.) D. Ovicell with the 

 oeciostome (oc), X 25. (After Waters, 1914.) E. Dorsal, X 20. F. Sketch showing details 

 >f ovicell (o), and porous windows (w), X 20. (After Harmer, 1915. ) G. Zoarium, natural 

 size. (After Waters, 1914.) 



Genotype. Erkosonea semota, new species, Jacksonian. 



The dactylethrae are the aborted tubes, since they are closed by a calcareous 

 membrane and do not contain a polypide. They have the same diameter as the 

 ordinary tubes and grow in the vicinity of the base of the lower tubes (and not 

 at different heights as the tergopores) ; they become branched but rarely. 



These dactylethrae characterize the family Clausidae D'Orbigny, 1853, but 

 Gregory noted no idmoneiform genus. 



Tubulipora camp/cheana Waters. 1887, of which the ovicell is known, must be 

 put in a genus close to Erkosonea. The ovicell is very close to that of Mes&nea. 

 Erl-oxonctt. differs from that genus in the presence of dactylethrae instead of 

 tergopores. 



ERKOSONEA SEMOTA, new species. 

 Plate 13?., figs. 1-13. 



Description. The zoarium is idmoneiform, linear, bifurcated, with oval trans- 

 verse section. The fascicles are quite sa lient, scattered. Formed of five zooecia, 



