448 Transactions. — Geology. 



and brown crystals of calcareous spar, with which all the 

 hollows of the septaria were lined or filled. Some of these 

 masses were hollowed out by the action of the waves into 

 regular basins, which at lowtide stand up from the sands full 

 of water, and are 3 ft. or 4 ft. deep." 



He then notices the zones or belt of cone-in-cone clav 

 with which they were encircled, and gives diagrams and sec- 

 tions. The diagram is interesting as showing a fragment 

 of bone, not in the centre, as a nucleus, but close to 

 the outer edge. The septarium is a small one in this 

 instance, being 2 ft. in diameter, and the piece of bone 

 enclosed ran straight into the mass. The fragment of bone 

 w 7 as flattened, li in. in longest diameter; "its cancellated 

 structure appears to resemble that of the moa." A note ap- 

 pended by Dr. Mantell (see below) states that slices prepared 

 for examination under the microscope showed the bone to 

 be avian. It would be of great interest to have the frag- 

 ment re-examined, as neither Dr. Mantell, Mr. Tomes, nor 

 Mr. Bowerbank do more than state that the microscopical 

 characters show that the bone belonged to a bird. Dr. 

 Mantell was not aware at that time of the occurrence of 

 reptilian bones in nodules and boulders at Katiki, the 

 Amuri Bluff, and in similar beds in other places. The 

 probabilities are, I think, more in favour of its being rep- 

 tilian than moa, more especially as no moa-bone has since 

 been found in beds of equal age. The fragment is, I believe, 

 still in the British Museum. 



Since their discovery the remarkable character of these 

 septaria has attracted successive generations of visitors, 

 and nearly all the smaller specimens have been removed to 

 adorn (?) the corners of paths and the grottoes of the subur- 

 ban villas of the ingenious. Many years ago an attempt was 

 made by the late Mr. J. T. Thomson to manufacture cement 

 from them, a proceeding probably suggested by the analysis 

 given by Dr. Mantell, and made at the Museum of Practical 

 Geology in London, showing 66-7 per cent, of carbonate of 

 lime. Dr. Mantell also compared them with the septaria 

 extracted from the London clay on the coast of Sussex, 

 which are made into first-class Boman cement. They occur 

 in abundance in the Isle of Sheppey, and are dredged for off 

 Harwich and in Chichester Harbour. 



Judging from the sketch given by Mr. Mantell, the septaria 

 were at the time of his visit well exposed. At the present 

 time the sand appears to shift very frequently, and at times 

 nearly covers the boulders. My photographs (see plates) 

 were taken at lowtide, and show that at present about 

 half of each stone is visible. There is one well down 

 between tide-marks which is much broken on the landward 



