98 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Occurrence. — 



D. 5134. Balukbaluk Island, Sum Archipelago; C° 44' 45" N.; 



121° 48' E.; 25 fathoms; fine S. 

 D. 5135. Jolo Light, Jolo; 6° 11' 50" N.; 121° 08' 20" E.; 161 



fathoms ; fine co. S; 14.1° C. 

 D. 5145. Jolo Light, Jolo; 6° 04' 30" N.; 120° 59' 30" E.; 23 



fathoms; co. S. Sh. 

 D. 5202. Limasaua Island, Sogod Bay, southern Leyte Island; 



10° 12' N.; 125° 04' 10" E.; 502 fathoms; gy. M. 

 Cotypes.— Cat. Nos. 7871, 7872, U.S.N.M. 



VIBRACELLINA CRASSATINA, new species 



Plate 7, figs. 3, 4 



Description. — The zoarium surrounds grains of sand. The zooecia 

 are distinct, separated by a deep furrow, elongated, pyriform; the 

 mural rim is a small, salient collar, thin; a thick cryptocyst surrounds 

 the opesium; the opesium is oval, anterior, entire. The ovicell is 

 endozooecial. The vibraculum is interzooecial, large, auriculated, 

 placed in the axis of the proximal zooecium. The ancestrula is small 

 with thick mural rim. The marginal zooecia are closed or regen- 

 erated. 



Measurements. — 



Large zooecia] T „ n ir^^ x n _ 



, ..i. .1/2 = 0.45 mm. _ . k = 0.25mm. 



without,, ftWmm Opesiumi, 

 •i. i \ \l>2 = v.S2 mm. r to = 0.15 mm. 



vibracula) J l 



Structure. — The zooecia of the ancestrular side are normal. On the 

 other side not only are the zooecia reversed with respect to the primi- 

 tive ancestrula but they almost all are closed and perforated by a 

 simple median pore. While in Cupularia and Lunularia, this kind of 

 cell (which we suppose to be hydrostatic and D'Orbigny called 

 aborted) is at the center of the zoarium, here it is marginal, but the 

 functions appear to be identical. 



The zooecia of the non-ancestrular face, which are reversed with 

 respect to the ancestrula, do not contain series of primitive zooecia. 

 In reality, they are oriented in the same manner and in the same 

 direction. This disposition is necessary for the hydrostatic equilib- 

 rium of the system as in Cupularia and Lunularia. The ectocyst 

 entirely surrounds the zooecia and the grain of sand; the latter is 

 incorporated in the colony absolutely as in the aforesaid genera. 



This species differs from Vibracellina capillaria and from V. viator 

 in the thick margin which surrounds the opesium. 



Occurrence.— D. 5144. Jolo Light, Jolo; 6° 05' 50" N.; 121° 02' 

 15" E.; 19 fathoms; co. S. 



Holotype.— Cat No. 7874, U.S.N.M. 



