Inglis. — On the Diatomaceous Deposits of New Zealand. 341 



Lake Sumner, North Canterbury. 



About ten or twelve years ago Mr. John Eussell, then of Lake Sumner 

 Station, observed on the margin of a tiny rill, on his run, on the hill slopes, 

 on the southern side of the lake, and about two hundred feet above the pre- 

 sent water-level, some dry whitish lumps of earth, which he brought to 

 Christchurch and submitted to the inspection of Dr. von Haast and me. 

 Dr. von Haast informed him of its diatomaceous character, and as I had 

 the opportunity of visiting the neighbouring station shortly afterwards, I 

 arranged with Mr. Eussell to visit the spot. I found the vegetable mould 

 and deposit cut into by the rill to the depth of two or three feet, laying 

 the latter bare. The terrace land falls back at this point from the lake, 

 and taking an easterly sweep, at an elevation of about three hundred feet, 

 towards the "Big Brother" Mountain, allows space for Lake Katrine, and 

 opposes a barrier to the discharge of Lake Sumner, with which it is con- 

 nected by a narrow channel, in that direction. The waters of Hurunui 

 Biver pass through Lake Sumner, and discharge themselves between the 

 farther side of the " Big Brother " and the mountains on the Nelson side of 

 the river, and through a huge clay bank. It appears therefore probable 

 that this deposit has been made at a long past period of the lake's history, 

 when its level was much higher than it is at present. 



The deposit is very rich in many fine forms, and two species new to 

 science have been found in it. On various occasions I have supplied 

 samples of the earth, and some of them have found their way into the 

 hands of English diatomists, and through their instrumentality the new 

 forms have been described. 



Triceratrum trifoliatum, Cleve, n.s. 



This form is unique and very remarkable. It is figured and described 

 in the " Boyal Microscopical Journal" for June, 1881, by Dr. Stolterforth, 

 under the name Hydrosera tricoronata as obtained " from a sub-peat fresh- 

 water deposit, North Canterbury. The exact locality not known." I have 

 ventured to suggest its lacustrine origin. 



The description given by Dr. Stolterforth is as follows : — 



" Filamentous. Front view of valves nearly quadrangular, showing 

 four ridges and a deep central depression, distinct connecting band ; side 

 view trilobate, each lobe having three projections or minor lobes. The 

 lobes are finely dotted, no regular markings on the central hexagonal por- 

 tion." 



Professor Cleve has also described the species shortly prior to Dr. 

 Stolterforth, hence the name attached. 



Plate XXIX., fig. 1, a side view, b front view. 



