260 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



it enlarges a little laterally and bears before the aperture a large 



avicularian umbo, covering the tremopores and hiding a large part 



of the aperture. The aperture is semielliptical; the proximal border 



is straight and bears a narrow pseudolyrula and two salient cardelles; 



the peristome is very thin. On the inferior face each zooecium bears 



a large perforated area accompanied by 2 to 4 radicular pores; the 



area is transverse and measures 0.20 mm. in width. 



Measurements. — 



. (Aa =0.20 mm. „ . fig =0.90-1.00 mm. 



Aperture, OA Zooecia 7 _ -_ _ ,- n 



Ua =0.30 mm. [lz =0.60-0.70 mm. 



Affinities. — This species is very well characterized by the aspect 



of its frontal and by its very small pseudolyrula. It is rare. Our 



specimens were dead. 



Occurrence. — 



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



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



D. 5580. Sibutu Island, Darvel Bay, Borneo; 4° 52' 45" N.; 



119° 06' 45" E.; 162 fathoms; br. S. co.; 13.2° C. 



Cotypes.—C&t. No. 8005, U.S.N.M. 



PETRALIELLA ROBUSTA, new species 



Plate 26, fig. 3 



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

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

 frontal is very convex and covered with large expanded tremopores; 

 the shield is little developed distally but the avicularian mucro is 

 very well developed, enormous, robust, bifurcated, covering the 

 aperture, with an oblique, lateral mandible. The aperture is semi- 

 elliptical, transverse; the proximal border bears two lateral inden- 

 tations limited by two small cardelles placed very low. 



Measurements. — 



(7wz=? „ . \Lz =1.10-1.25 mm. 



Aperture 7 Zooecia 7 _ ._ 



Ua =0.40 mm. U2 =0.65 mm. 



Affinities. — This species differs from Petraliella vultur Hincks, 1882, 

 in the absence of spines and in the presence of a nonstriated avicu- 

 larian umbo, much larger and bifurcated. Our specimens were dead. 



Occurrence— ~D. 5162. Tinagta Island; 5° 10' N.; 119° 47' 30" 

 E.; 230 fathoms; S. brk., Sh. era.; 24.2° C. 



Holotype.— Cat. No. 8006, U.S.N.M. 



PETRALIELLA ARMATA Waters, 1913 



Plate 25, figs. 1, 2 

 1913. Petralia vultur var. armata Waters, Bryozoa from Zanzibar, Proceedings 

 Zoological Society of London, p. 518, pi. 70, figs. 15-20. 



Measurements. — 



. [Aa=0.25mm. „ . (Z,s = 1.25 mm. 



Aperture 7 Zooecia 7 _ ■ 



r Ua =.n SO mm. \lz =0.50 mm. 



