384 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



arranged on the median axis. The cribriform area is small, elliptical, 



perforated by 5 stellate pores. The frontal avicularium is very 



large, jalcvform, very narrow. Its length is at least half that of the 



zooecium. The apertura of the gonoecia is much wider (0.12-0.14 



mm.). 



Measurements. — 



. . \ha -0.07 mm. „ . \Lz =0.55-0.60 mm. 



Aperturai, . ,_ Zooecia, n _ n ~ „ 



^ Ua=0.10mm. \lz =0.30-0.35 mm. 



Width of fronds, 2.5 mm. 



Occurrence. — D. 5217. Anima Sola Island, between Burias and 



Luzon; 13° 20' N.; 123° 14' 15" E.; 105 fathoms; crs. gy. S.; 17.2° C. 



Cotypes. —C&t. No. 8188, U.S.N.M. 



Genus DIMORPHOCELLA Maplestone, 1903 



Adeonidae having an oral sinus for the opening of the compen- 

 satrix. The gonoecia are large, provided with a polypide, with an 

 ascopore and with ovarian organs. 



Genotype. — Dimorphocella (Adeonella) triton MacGillivray, 1895. 

 Miocene. 



The known species belonging to this genus are the following : 



Dimorphocella triton MacGillivray, 1895 Miocene. 



Dimorphocella pyrijormis Maplestone, 1903 Miocene. 



Dimorphocella (Schizoporella) submersa Waters, 1881 Miocene. 



Dimorphocella differs from the genus ScMzostoma Canu, 1907, in 

 the presence of an ascopore (and consequently of a polypide) on 

 the gonoecia. 



Historical. — Maplestone, 1913, added to his genus, Dimorphocella 

 portmarina Maplestone, 1913, a recent species. In 1920 we followed 

 him with some reservations. Now we think that Dimorphocella 

 portmarina is a true Adeona although its zooecia like its gonoecia are 

 perforated by an ascopore. It is however deprived of the frontal 

 avicularium, rather constant in the other species of the genus. Future 

 studies may permit us perhaps to make it the genotype of a new genus 

 when the physiologic functions of the frontal avicularium will be 

 better known, but it is necessary to remove this species from Dimor- 

 phocella. 



Genus BRACEBRIDGIA MacGillivray, 1886 



BRACEBRIDGIA FISSIFERA, new species 



Plate 50, figs. 9, 10 



Description. — The zoarium is free, bilamellar; the fronds are com- 

 pressed, undulated, rarely flat, dichotomous, branching like the 

 horns of a deer. The zooecia are distinct, separated by a deep 

 furrow, elongated, pyriform; the frontal is smooth, little convex, 

 surrounded by a line of parietal dietellae. The peristomice is elon- 

 gated, elliptical. A small oblique, triangular avicularium is lodged 



