428 Transactions. 



of the soundings taken before and during dredging in the area of the harbour 

 concerned. 



Dealing with the suggestion that portions of the Waitemata beds have 

 been dislodged and brought up, it need only be mentioned that the dredge 

 employed was of the suction type and quite incapable of disrupting the 

 coherent Waitemata sandstones disclosed beneath the silts by boring. The 

 possibility of the concretions being a rewash of the Waitematas has already 

 been considered. 



The Harbour Board bores and the more recent physiographic history 

 of the Auckland area prove, in the writer's opinion, that the concretions 

 belong to beds now forming, which have had an uninterrupted course of 

 deposition since their inception. 



The pertinent facts of the recent physiographic history of Auckland 

 are that the Auckland Harbour represents a former stream-valley drowned 

 by invasion of the sea within fairly recent geological times, and that, sub- 

 sequent to the drowning, the only recognizable movement of elevation 

 (evidenced by wave-cut platforms) is one involving an uplift of not more 

 than 5 ft. or 6 ft. 



The bores demonstrate that the concretion-bearing sediments occur in 

 a steep-walled narrow gut, with its bed approximately 30 ft. below mean 

 low-water level (the Harbour Board datum), flanked by a level platform 

 of firm sandstone (Waitemata) approximately 3 ft. or 4 ft. below low-water 

 level. This gut is a continuation of the well-marked gulch spanned by 

 Grafton Bridge. Gut and platform alike, prior to the commencement of 

 dredging, were masked by sands and muds which raised the harbour-bottom 

 to within about 2\ ft. of low-water level. The filling of the gut was every- 

 where unconsolidated. 



Auckland, 24th August, 101/. 



Art. XXXIV. — Kermadec Island Fleas. 

 By F. W. Hilgendorf, D.Sc. 



[Received by Editors, 30th December, 1916 ; issued separately, 30th November, 1917.] 



In 1908 Mr. W. R. B. Oliver brought back from the Kermadec Islands 

 two species of fleas, and the fact that these have never been recorded 

 has been overlooked. One of the fleas was found on a sandy beach, and the 

 other on Mus exulans, the Maori rat. The identifications were kindly made 

 by Lord Rothschild. 



Pysgiopsylla hilli is an Australian flea which has been found on the 

 mainland of Australia on several hosts. It has not been recorded fiom 

 beyond the Australian region. 



Xenopsylla cheopis is of wide distribution, being the common tropical 

 flea on rats. It is instrumental in spreading plague, and is found in 

 practically all warm countries. There is apparently no record of this or 

 any other flea having been taken from Mus exulans in New Zealand. 



