504 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



,- , A [ ha = 0.07 mm. 



Measurements. — Aperture 7 _ _„ 



^ Ua = 0.07 mm. 



Affinities. — This species differs from Flabellopora tuberosa in the 

 absence of a parietal area and peristome, in smaller oral dimensions, 

 and in the lenticular form of the colony. There are other species with 

 small orbicular colonies but none of them is ornamented with large 

 tuberosities. 



Occurrence. — D. 5579. Sibutu Island, Darvel Bay, Borneo; 4° 54/ 

 15" N.; 119° 9' 52" E.; 175 fathoms; fine S., co.; 13° C. 



Cotypes.— Cat. No. 8312, U.S.N.M. 



FLABELLOPORA ACUTA, new species 



Plate 73, figs. 1-5 



Description. — The zoarium is free, arrow-shaped; the angle of the 



initial base is much broader than the terminal angle, which is quite 



acute; the length varies from 5 to 9 mm. The avicularia which 



decorate the external wall of the zooecia are poriform with salient 



peristome; they are almost regularly arranged two and two between 



the apertures and in their median axis. The aperture is orbicular; 



the peristome is thin and salient; the proximal pore is small and 



placed on the peristome. 



. [7mi = 0.09-0.11 mm. 



Measurements. — Aperture 7 _ „„ _ , , 



1 I la = 0.09-0.11 mm. 



Structure. — The zoarial form is rather variable; there are broad 

 colonies and also very narrow colonies but the terminal angle always 

 remains acute. 



In spite of appearances the avicularia and the apertures are not 

 arranged together longitudinally. The oblique rows of apertures 

 are separated by a double parallel row of alternating avicularia. But 

 the architecture is so perfect that the appearance is deceiving. 



Very often the proximal pore is united with the aperture; the latter 

 then takes a false schizoporoid aspect, but with the microscope it is 

 easy to prove that the proximal sinus thus formed has no depth. 



The avicularia are formed by small adventitious orbicular cells 

 very visible in the longitudinal section. 



We have prepared an excellent meridian section which shows 

 that the internal structure is a true master piece of geometry. The 

 interior show well an orbicular aperture without any apparent sinus. 



Affinities. — This species differs from Flabellopora tubifera in its 

 larger aperture, in its avicularia less numerous and non salient tube. 



Biology. — This species was dredged only in the single locality of 

 Tubig Point, at the western extremity of Bernardina Channel. This 

 locality has furnished us only a very small fauna of bryozoa of small 

 dimensions and of original forms. 



Occurrence.— D. 5392. Tubig Point, Destacado Island; 12° 12' 

 35" N; 124° 02' 48" E.; 135 fathoms; Gn. M., S. (common). 



Cotypes— Cat. No. 8313, U.S.N.M. 



