Groirfh and Habits of Biporae. 5 



obtained, and that is a niatter of some difficulty, because these 

 conical forms are only found at depths of from 80 to 250 

 fathoms, and are so small that when dredged up that they 

 might not be discovered in time to properly preserve them. 



Another structure in these Jii/xirae which has puzzled me, 

 and also Professor Harmer, is the " semi-lunar slit " which Mr. 

 Whitelegge considers to be the commencement of a new zooe- 

 cium. He gives a very circumstantial account of it and its 

 development into zooecia, but I have not been able to discover 

 any instances of such development in any of the specimens I 

 have examined. This " slit " he reports as being seen in all 

 stages of its development in Bipora jjhilipjnnensis, but in a 

 slide which he sent me some years ago containing some 40 

 specimens of that species I could only find it on two small 

 highly calcified fragments ; though subsequently on a slide, lent 

 me by the Curator of the Australian Museum since I examined 

 the " Miner " polyzoa, there were several specimens of this 

 species, in most of which the semi-lunar slit was present in what 

 I take to be the perfect or complete state. (See Fig. 2.) I 

 could not find in any of them an imperfect or younger form. 

 These slits surround a nearly circular flap, the base of which is 

 connected with the surface of the zoarium by a raised nodular 

 process, and I consider it is improbable that such as are present 

 in the specimens c(5uld eventually be continued, so as to com- 

 plete the circle, through this thickened process, and cause the 

 flap to fall off, and even if they did, the opening would not cor- 

 respond in either size or shape with the ordinary peristomial 

 orifice ; and if, as Mr. Whitelegge states, there were underneath 

 this external orifice an oral opening, it would indicate the for- 

 mation of a zooecium considerably below the surface of the 

 zoarium, in no way contributing to its " growth in size." Now 

 if the theory that the .semi-lunar slit is always the com- 

 mencement of new zooecium be correct, it should be found 

 in all the various species of Biporae. Mr. Whitelegge records 

 it in B. anyulojjora and in B. elegans (in addition to B. 

 philippintmis already alluded to), and states that it is nut seen 

 in any specimen of B. timbonata, in the Australian Museum, 

 which is the species in respect of which he states Professor Has- 

 well's description of the "different forms of the mouth "' showed 



