Mr. A. W. Waters on Australian Bryozoa. 7 
depression (fig. 11, lower zocecium), and in these mature zocecia 
there are, as seen in calcined specimens, deep grooves between 
the stellate pores, starting from large pores near the borders of 
the zocecia. One of these grooves seems usually to start from 
the upper lateral pore on the one side and pass above the sub- 
oral pore to the lateral pore on the other side, as shown in the 
left-hand zocecium of fig. 11. Decalcification shows distinct 
tubes occupying the place of these grooves. The interior 
membrane of the zocecial wall is perforated by the suboral 
pore, but not by the others. 
As already pointed out, the operculum is the reverse of the 
usual shape, and when writing the previous description I 
naturally concluded that it was hinged on the distal edge and 
not at the proximal, as in other Bryozoa; but not having very 
good specimens, I merely presumed it, and it would seem to 
me that what I wrote suggests this; but it does not seem to 
have been so understood by Mr. Whitelegge, who, having 
had the opportunity of examining fresh specimens, points out 
that the aperture is of the same shape as in other Bryozoa, but 
reversed. I have certainly no objection to its being put in 
this way, but do not appreciate that it is different from what I 
said; and the name dtnversa was chosen on account of this 
reversal of shape, so that Mr. Whitelegge’s and my own 
description seem quite the same though expressed in a different 
way. 
Dr. Jullien * described a species as Inversiula nutrix about 
the same time that I published my description ; and at first I 
thought they might be identical. The general appearance 
is so similar that they might readily be mistaken; but 
the individual characters must be examined, and then a mate- 
rial difference is found in the shape of the oral aperture, which 
in J. nutriv is nearly round but somewhat flattened on both 
the distal and proximal edges, and I am inclined to think 
that the operculum is here also reversed in position. I cannot 
speak on this point with certainty, as I have only been able to 
examine a very minute fragment, and have not made dissec- 
tions. Dr. Jullien only possessed a small piece, but gene- 
rously sent mea little bit of it for examination. 
The suboral pore of Inverstula nutrix I should describe as 
round, with a tooth in the lower part, as in many Micropo- 
rellide. One suboral pore without any such tooth is quite 
round, and the difference in this character in Jullien’s species 
and mine does not seem of any generic importance. 
In M. inversa I have only seen the small semicircular 
* ‘Mission du Cap Horn,’ Bryozoaires, p. 44, pl. iy. fig. 8. 
