BRYOZOA OF THE PHILIPPINE REGION 117 



Affinities. — The orifice is regular; it corresponds rigorously to the 

 form of the opercular valve attached to the ectocyst, placed below 

 the frontal. Our specimens were dead and we have not been able to 

 verify the degree of chitinization of the valve. 



This species differs from Hiantopora liversidgei MacGillivray, 1895, 

 in its more numerous frontal pores and its much broader zooecia. 



Biology. — This is a species of deep waters. It is larger and more 

 calcified than Hiantopora bidenticulata from waters of less depth. 

 This is a frequent rule in the Tropical Zone. As the specimens were 

 unilamellar, it is not certain that they were living in the depths 

 where they were dredged. 

 Occurrence. — 



D. 5137. Jolo Light, Jolo; 6° 04' 25" N.; 120° 58' 30" E.; 20 



fathoms; S. Sh. 

 D. 5577. Mount Dromedario, Tawi Tawi; 5° 20' 36" N.; 119° 



58' 51" E.; 240 fathoms; crs. S.; 12.4° C. 

 D. 5579. Sibutu Island, Darvel Bay, Borneo; 4° 54' 15" N.; 

 119° 09' 52" E.; 175 fathoms; fine S., co.; 13° C. 

 Cotypes.—CsLt. No. 7917, U.S.N.M. 



Genus TREMOGASTERINA Canu, 1911 



This genus was discovered by Canu in 1911 in the Cretaceous rocks 

 (Rocanean) of Argentina. Its discovery in the Philippines permits 

 a description of its structure. It belongs to the special group in 

 which the zooecia are entirely membraneous but covered with a 

 cellular carapace or pericyst. In its large trifoliate frontal pore and its 

 large interzooecial avicularia it approaches Hiantopora; but this is 

 only an exterior aspect which is not trustworthy. Here the operculum 

 appears to indicate the existence of a compensatrix, an organ which 

 has not yet been really noted in Hiantopora and which is lacking 

 surely in Tremopora. 



The same phenomena can be observed in the artificial group of the 

 Costules. MembraniporeUa, Cribrilina, and Figularia have also an 

 internal ectocyst but Figularia alone has a compensatrix. Tremo- 

 gasterina would perhaps be better classed next to Figularia. 



The study of these fantastical forms leads us to the consideration 

 of a new product of calcification, the pericyst, an addition to the 

 tremocyst, olocyst, and pleurocyst already known. 



But ns its origin is still obscure, further researches are necessary. 

 It is certain now that the presence of costules can not be considered 

 as ii family character. 



We published a special study of this genus in our Gulf of Mexico 

 report in 1928, although in the text of this work it is now necessary 

 to replace pleurocyst by pericyst. 

 2182—29 9 



