BRYOZOA OF THE PHILIPPINE REGION 123 



EXECHONELLA DISCOIDEA, new species 



Plate 20, figs. 5, 6 



Description. — The zoarium is discoidal, free, small. The zooecia 

 are distinct, separated by a deep furrow, elongated, oval; the frontal 

 is very convex and perforated by large pores with salient peristomes; 

 the peristomie is long, smooth, oblique, tubular. The peristome is 

 thin, orbicular, entire, laciniated or crenulated. The ovicell is small, 

 punctured by small pores and opens into the peristomie above the 

 apertura. 



Measure merits . — 



t, . . . ffan = 0.30mm. „ . fi2=l.lmm. 



Penstomice 7 . on ZooeciaU n 



[lpi = 0.30 mm. [Iz = 0.65 mm. 



Affinities. — The long and tubular peristomie characterizes very well 

 this species. The ectocyst is not visible; it is buried under the 

 frontal. The frontal pores with the salient peristome are not tremo- 

 pores for they are never traversed by the mesenchymatous fibers. 

 According to Levinsen, 1909, these are lacunae left between the primi- 

 tive costules, perfectly and regularly united together. Our specimens 

 were dead. 



Occurrence. — D. 5235. Nagubat Island, east coast Mindanao; 9° 

 43' N.; 125° 48' 15" E.; 44 fathoms; sft. M. 



Division 3, COILOSTEGA Levinsen, 1909 



Family OPESIULIDAE Jullien, 1888 



Subfamily Onychocellidae Jullien, 1881 



Genus ONYCHOCELLA Jullien, 1881 



For description see Canu and Bassler, 1920. North American Early Tertiary 

 Bryozoa, Bull. 106, U. S. National Museum, p. 105. 



We have recently undertaken a revision of the known species and a 

 more detailed study of specimens covered by their ectocyst. We 

 have observed the following facts. 



1. The dimensions of the opesium are quite variable. When 

 the large opesia are adjacent to the smaller opesia a false appearance 

 of opesial dimorphism appears (Onycliocella dupliciter Canu and 

 Bassler, 1920). In reality there are opesia of all sizes between these 

 extreme cases. Often the elongated opesia are those of ovicelled 

 zooecia. 



2. The size of the opercular valve is constant and without relation 

 to that of the subjacent opesium. This valve is more or less removed 

 from the distal border of the zoarial mural rim. 



3. The opesiular indentations are quite variable in the same 

 species and according to the species. They are very little apparent 

 in the species in which the proximal border of the opesium is concave. 



