BRYOZOA OF THE PHILIPPINE REGION 259 



all the aperture; there is no shield. The aperture is large, trans- 

 verse; its proximal border is straight and bears laterally two inden- 

 tations limited by two small cardelles; the peristome is very thin, 

 little visible. On the inferior side the zooecia bear distally 2 radicular 

 pores and a perforated area a little larger (0.10-0.15 mm.). 

 Measurements. — 



[7ki = ? v . J£z = 1.10-1.35 mm. 



Aperture (^ _ Q 5Q mm Zooecia [^ ^ Q90 _ im mm 



Affinities. — This species differs from Petraliella gigantea in the 

 absence of a shield and in the enormous bifid avicularian umbo. 



Biology. — Our specimens were dead. Sibutu (283 meters) is the 

 home of the giant Petraliella. They appear to have found here the 

 most favorable conditions for their development. 



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

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



Cotypes.— Cat. No. 8003, U.S.N.M. 



PETRALIELLA ELONGATA, new species 



Plate 24, fig. 8 



Description. — The zoarium is unilamellar. The zooecia are dis- 

 tinct, separated by a deep furrow, very much elongated, elliptical; the 

 frontal is convex and punctured with widened tremopores; the 

 bipartite shield is wide, convex and bears a little salient avicularian 

 umbo before the aperture; two or three small avicularia appear on the 

 shield. The aperture is semi elliptical, transverse; the proximal 

 border is straight and bears two small lateral indentations limited by 

 two small inequal cardelles. The peristome is thin. There are small 

 elliptical avicularia irregularly placed around the aperture. On the 

 inferior face there is only a small distal radicular pore on each zooecium. 



Measurements. — 



(7wi=0.25mm. „ . \Lz =1.40-1.50 mm. 



A P erture U =0.30-0.35 mm. Z ° 0eCia U =0.70 mm. 



Affinities. — This new species differs from Petraliella gigantea in its 

 smaller measurements and in its smaller and more numerous tremo- 

 pores. Our specimens were dead and non ovicelled. 



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

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



Holotype.—C&t. No. 8004, U.S.N.M. 



PETRALIELLA TRITA, new species 



Piute 24, figs. 5-7 



Description. — The zoarium is unilamellar. The zooecia are dis- 

 tinct, separated by a deep furrow, elongated, elliptical ; the frontal is 

 convex, covered with small tremopores, separated by smooth inter- 

 vals giving them a worn aspect; the shield is reduced to a distal line; 



