BRYOZOA OF THE PHILIPPINE REGION 97 



This species has a quite bizarre aspect. It was ovicelled in 

 November 1904. 



Occurrence.— D. 4807. Cape Tsiuka, Sea of Japan; 41° 36' 12" 

 N.; 140° 36' E. 



Cotypes.— Cat. No. 7870, U.S.N.M. 



Genus VIBRACELLINA Canu and Bassler, 1917 



VIBRACELLINA VIATOR, new species 



Plate 7, figs. 1, 2 



Description. — The zoarium incrusts small orbicular pebbles which 

 it covers almost entirely. The zooecia are distinct, separated by a 

 deep furrow, elongated, somewhat oval; the mural rim is thin, 

 smooth, filiform; the opesium is large and of the same form as the 

 zooeeium. The ovicell is very small. The vibraculum is small, 

 auriculate, interzooecial placed in the axis of the proximal zooecium. 

 The ancestrula is always placed eccentrically. 



Measurements. — 



T • JZ2 = 0.42mm. ^ ■ fJ?o = 0.35mm. 



Large zooecium-L Opesium L 



iZz = 0.25mm. F lZo = 0.20mm. 



Biology. — This species is almost similar to Vibracellina capillaria 

 Canu and Bassler, 1920, from the Claibornian of Texas and it differs 

 only in its very small vibracula. 



This is a small hydraulic wonder. The larva almost always affixes 

 itself on small grains of sand (very rarely on fragments of shells), 

 where it places itself eccentrically. Here it develops, and the colony, 

 having covered the superior face, invades the inferior face. On the 

 latter the zooecia are placed in an inverted position as if they radiated 

 from an inaginary center, but they do not entirely cover it. How- 

 ever the ectocyst entirely covers the grain of sand and it is by its 

 protection that the inversion can be made. The colony entirely 

 developed, travels with its substratum and its vibracula assure the 

 stability of all the system. The promenade is not long for we have 

 not observed the species in many localities. The colony is not a 

 reunion of zooecia but is an entity in itself. Species of Vibracellina, 

 like Cupularia and Lunulites demonstrate perfectly the biological 

 unity of the colony derived moreover from a single larva. It is very 

 probable that the larva chooses its own substratum, for so far we have 

 never observed this species on a large pebble. Vibracellina capillaria 

 incrusted only very small shells (never grains of sand) and we have 

 never observed it on large shells. It is an instinct wholly comparable 

 to that in the insects. 



Vibracellina is an elementary incomplete Cvpuladria. The sub- 

 stratum is necessary for its life, while in Cupuladria it is necessary 

 only at the birth of the colony. The present species lives at depths 

 varying from 37 to 813 meters. 



