342 NOTES ON SOME AUSTRALIAN POLYZOA, 



When the zoojcia are seen in transverse section the outline of 

 each zooecium is irregularly pentagonal. 



The anterior pore, when seen from within, appears as a flask- 

 shaped projection on the cell-wall, and is about as long as the 

 shorter diameter of the mouth ; in some tliere appears to be an 

 opening, and in others the base is well rounded without any opening ; 

 it may possibly be the retreat of a protrusible sensitive organ, but 

 in no case have I seen anything at the upper extremity which 

 would indicate the presence of an external vibracular organ. The 

 cancellate structure, which exists more or less in all the species, may 

 originate by the lower portion of the zocecia being continually 

 partitioned off as the zoarium increases in size. 



In some of the specimens lent by Mr. Brazier the ooecia are 

 fairly abundant, but, except the zoarium is broken into two halves 

 or set on its edge, the orifice cannot be seen. From this fact it 

 will be evident that they are in the usual position above the mouth, 

 and nearest to the primary part of the zoarium. 



(3.) B. DEPRESS A, Haswell. 



Gonescharellina depressa, Hasw. Proc. Linn. Soc. N.S.W. 1880, 

 Part I, Vol. y, p. 41, pi. Ill, fig. 4. 



Zoarium biconvex, slightly flattened beneath ; oral aperture 

 elongate, rounded above, with a sinus below, about half the 

 diameter of the mouth ; or ovate with a sub-triangular denticle on 

 each side near the base. Operculum ovate with a very slightly 

 thickened border and two circular spots on the upper half . 

 peristome much elevated above, and on each side to below the 

 mouth, then suddenly depressed ; an avicularium with an elongate 

 triangular mandiljle situated on a low elevation on one side of the 

 mouth. 



" Under surface of zoarium perforated by close-set circular pores, 

 each occupied, either at the surface or at a varying depth, by a thin 

 translucent covering perforated by several minute porules, usually 

 with a rather larger one in the centre." 



Loc. — Port Denison. 



