508 . BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



border. But all the concentric series without exception are borne 

 upon the branches of the initial V which is the equivalent of the basal 

 lamella of the other cheilostomata. It is also the same in the section 

 of Orbitulipora excentrica. 



This species is very well characterized by its very constant zoarial 

 form. # 



Biology. — This form is very divergent from the preceding forms 

 studied. This locality is far from the China Sea and the Sulu Sea 

 which is a division of it. We are thus obliged to admit that the con- 

 figuration of the sea exercises an indisputable influence on its own 

 fauna. 



Occurrence.— D. 4807. Cape Tsiuka, Sea of Japan; 41° 36' 12" N.; 

 140° 36' E. 



Cotypes.—C&t. No. 8318, U.S.N.M. 



FLABELLOPORA ASPER, new species 



Plate 75, fig. 1 



Description. — The zoarium is free, small, suborbicular, 2 to 3 mm. 

 in diameter; the angle of the initial base is small and there is no 

 terminal angle. The external walls of the zooecia are ornamented 

 with an aperture, a small avicularium placed distally and close to an 

 aperture and a much larger poriform avicularium, arranged among 

 many asperities more or less salient. The aperture is small, orbicular, 

 with peristome little salient and arranged between two large zoarial 

 asperities; the distal sinus is little apparent; the proximal pore is 

 rather large and surrounded with a peristome adjacent to the oral 

 peristome. 



,, . [ha = 0.08 mm. 



Measurements. — Aperturei, 



^ lm = 0.08 mm. 



Variations. — Although very short the zoarium is clearly flabelli- 

 form and deprived of a terminal angle; it belongs then to the F. 

 transversa group. But it is perfectly characterized by its parietal 

 asperities. 



We have prepared some thin sections which confirm the preceding 

 observations; the internal structure of these flabellate forms is abso- 

 lutely identical with the structure of the forms provided with a 

 terminal angle. 



Biology. — This is one of the rare forms peculiar to the Celebes 

 Sea. It indicates however a beginning of the divergence which ought 

 certainly to be greater in the southeast in the vicinity of the Pacific. 

 Occurrence. — 



D. 5151. Sirun Island, Sulu Archipelago; 5° 24' 40" N.; 120° 



27' 15" E.; 24 fathoms; co. S., Sn. 

 D. 51G2. Tinagta Island, Tawi Tawi Group; 5° 10' N.; 119° 47' 

 30" E.; 230 fathoms; S. brk., Sh., crs. 

 Cotypes.—C&t. Nos. 8319, 8320, U.S.N.M. 



