106 PROCEEDINGS OF THE 



definitely showed that it was not identical with the New Zealand 

 form. He calls the Geelong species Taeniogyrus Allani. The 

 President referred to the varying nomenclature of these species. 

 He considered all the forms closely related, and preferred the 

 generic name Chiridota, applied by Parker to the New Zealand 

 form. The differences between the New Zealand and Geelong 

 species were then considered. The structure of the wheel spicule 

 had been worked out by Mr. Joshua, and was described in his 

 paper. The President had worked out the N.Z. form some years 

 ago, and described and sketched on the blackboard the various 

 stages observed. The spicule has a broad margin, corresponding 

 to the rim of the wheel. Then there are six spokes radiating 

 from the centre, and in some species there is a small hole in the 

 middle. Specimens of C. dunedinensis exhibit a uniform minute 

 toothing all round the margin, which is inturned. The other 

 side of the wheel has a different appearance. The six spokes 

 show as before ; but the toothed edge is not seen at the top 

 focus. Further, fresh detail is exhibited in the form of a 

 six-rayed cross, which stands above the level of the spokes. A 

 diagram of a vertical section was given. The President said it 

 was a very curious and wonderful structure, and the development 

 was of extreme interest. Commencing with the six-rayed cross, 

 a thickening appears at the end of each ray, and on one surface 

 only. This was the earliest stage observed. As the thickenings 

 grow, they exert pressure on each other, and presently each 

 spoke bifurcates at the extremity. The bifurcated ends begin 

 to grow outward, and presently meet, and, fusing, form the rim 

 of the wheel. The rim turns in, and is denticulated all round 

 the margin. The spicule is, of course, useful as a skeletal 

 structure ; but it is not at all apparent why such a remarkable 

 and elaborate form should be required. The chief differences in 

 C Allani, as compared with C. dunedinensis, are : The margin, 

 instead of rounding off, remains hexagonal. The face showing 

 the six-rayed cross is much the same, excepting that it also is 

 hexagonal ; but the toothed rim is not uniform, but follows 

 a curve with little bays opposite the angles of the hexagon, and 

 the toothing is pronounced in parts, but is absent from the bays 

 or notches. It is very difficult to account in any way for such 

 minute differences as those noted. The new form, which he 

 would prefer to call Chiridota Allani, was first found by Mr. 



