BRYOZOA OF THE PHILIPPINE REGION 261 



There are too great differences between t he figures of Hincks, 1882, 

 and Waters, 1913, to class them in the same species so we prefer to 

 recognize the variety as distinct. 



Our specimen has the general aspect shown in Waters's figures and 

 the differences are quite secondary; the measurements are a little 

 smaller and the large avicularium has a dissymetric beak. 



On the inferior face there are only small radicular pores; very fine 

 radieells were attached to a small fragment of alga; all the marginal 

 radicular pores distant from the alga were closed by a small mem- 

 braneous operculum. 



The avicularian umbo is erected almost perpendicularly to the zoo- 

 eeial plane; it is therefore in reality larger than it appears to be in the 

 figure. 



This charming species is very rare. Our specimens were living. 



Biology. — The species was in reproduction February 18, 1908. 

 The delicacy of its ornament and the multiplicity of the avicularia 

 indicate very calm waters. 



One of our opercula still retains an occlusor muscle; it is attached to 

 the internal sclerite as Waters has figured in Petraliella chuakensis 

 and is identical with that of Waters. 



Occurrence. — D. 5149. Sirun Island, Sulu Archipelago; 5° 33' N.; 

 120° 42' 10" E.; 110 fathoms; co. Sh. 



Plesioty 'pes. —Cat. No. 8007, U.S.N.M. 



PETRALIELLA PHILIPPINENSIS, new species 



Plate 25, figs. 3-11 



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

 tinct, separated by a deep furrow, elongated, elliptical or rectangular; 

 the frontal is convex and covered with widened tremopores grouped in 

 radial lines; the shield is very small distally, enlarged and rounded 

 laterally and bears before the aperture, a large avicularian umbo 

 dissymetric with oblique mandible. There are two small lateral 

 avicularia on the shield. The aperture is large, semielliptieal, trans- 

 verse; the proximal border bears a wide lyrula separated by two in- 

 dentations with two cardelles placed on the same line; the peristome 

 is thin and little salient; a very long spatulate avicularium appears 

 sometimes. The ovicell is buried in the distal zooecium and covered 

 with small tremopores. Some small sporadic avicularia appear ir- 

 regularly in the vicinity of the aperture distally. On the inner face 

 there is on each zooecium a perforated area of variable size accompa- 

 nied by one or many radicular pores. 



M< <isurements. — 



. \ha =0.24-0.28 mm. „ . \Lz =0.90-1.10 mm. 



Aperture , n nn Zooecia L A ._ n _„ 



Ua=0.30 mm. Us ■= 0.40-0. 70 mm. 



2182—29 18 



