Mr. A. W. Waters on Australian Bryozoa, 7 



depression (fig. 11, lower zooecium) , and in these mature zooecia 

 there are, as seen in calcined specimens, deep grooves between 

 the stellate pores, starting from large pores near the borders of 

 the zooecia. 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 tlie 

 left-hand zooecium of fig. 11. Decalcification shows distinct 

 tubes occupying the place of these grooves. The interior 

 membrane of the zooecial 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 1 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 tlie 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 inversa 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 /. nutrix 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 reveised 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 me a little bit of it for examination. 



The suboral pore of Inversiula nutrix I should describe as 

 round, with a tooth in the lower part, as in many Micropo- 

 rellida^. 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 tlie small semicircular 



* ' Mission du Cap Horu,' Bryozoaires, p. 44, pi. iv. fig. 8. 



