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BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



clavular and the ovicell is endozooecial without any separation from 

 the zooecium itself. The structure of the frontal is the usual structure 

 of the tremocyst. 



Affinities. — This species is very close to Tetraplaria australis 

 Tenison- Woods, 1878, and differs only in its larger aperture provided 

 with a wide sinus. It differs from Tetraplaria simplex Robertson, 

 1921, in the constant presence of separating threads. It differs from 

 Tetraplaria dichotoma Osburn, 1914, in its small ovicelled zooecia. 



Biology. — Our living specimens were ovicelled in July, 1909. As 

 they were dredged alive, they were indeed in the vicinity of 



the bottom. This species 

 therefore does not appear 

 to be parasitic on marine 

 algae, which is confirmed 

 moreover by the absence of 

 all zoarial appendages. The 

 articulation appears then to 

 be an adaptation to a more 

 or less rapid marine cur- 

 rent. The absence of zo- 

 oecial avicularium and the 

 proximity of the strait of 

 Surigao confirm this deduc- 

 tion. 



Occurrence. — 



D. 5235. Nagubat Is- 

 land, east coast of 

 Mindanao; 9° 43' N.; 

 125° 48' 15" E.; 44 

 fathoms; sft. M. 

 D. 5478. Tacbuc Point, Leyte; 10° 46' 24" N.; 125° 16' 30" 

 E.; 57 fathoms; Sh. (common). 

 Cotypes— Cat. No. 8403, U.S.N.M. 



Genus POLLAPLOECIUM Maplestone, 1908 



1908. Pollaploecium Maplestone, Polyzoa from Gilbert Islands, Proceedings 

 Royal Society Victoria, vol. 21, p. 417, pi. 28, fig. 18. 



The ovicell is endozooecial. The apertura is schizoporidan with a 

 small and deep sinus in the middle. The frontal is a tremocyst. 

 The zoarium is articulated. The segments are composed of six to 

 ten zooecia, united on their dorsal surface, facing all ways. 



Genotype. — Pollaploecium gilbertensis Maplestone, 1909. Recent. 



Genus DIPLOECIUM Kirkpatrick, 1888 



The ovicell is endozooecial. The aperture is schizoporidan with 

 notch in lower border. The frontal is marked with a mosaic pattern. 



Fig. 152. — Genus Pollaploecium Maplestone, 

 1908 



A, B. Pollaploecium gilbertensis Maplestone, 

 1909. A. Zoarium, X 12. B. Aperture, more 

 enlarged. (After Maplestone, 1909.) 



