Wall. — Ranunculus paucifolius T. Kirk. 93 



lidges and shallow hollows of dune type. The south-west half of the basin is 

 clothed with tussock grassland, and does not concern us. The north-east 

 half, at the south-west end, shows first (moving from south-west to north-east) 

 a small area, about 120 yards by 100 yards, of open debris formation which 

 does not harbour this Ranunculus. The upper (or north-eastern) portion 

 consists of a larger area of limestone debris, about 350 yards by 100 to 150 

 yards, of which some parts are clothed with a half-closed tussock formation, 

 others with an open formation, including the Ranunculus paucifolius, while 

 some considerable portions are entirely barren. The bottom of this part of 

 the basin is occupied chiefly by a belt of half-closed tussock formation ; the 

 eastern side has rapid slopes of coarse debris below the limestone rocks ; the 

 western side (shown in Plate IV) has a gentler gradient, and the grass-covered 

 slopes of Castle Hill here ease off gradually into the central basin. Tongues 

 of half-closed tussock formation, on this side, occupying higher ground or 

 ridges, separate roughly circular or semicircular areas of the open formation 

 well seen in Plate V, within which most of the plants of Ranunculus 

 paucifolius occur. 



The debris itself is of a flaky character, but is reduced, over most of 

 the area, to a fine uniform powder. The colour of the bare patches is thus 

 a pale yelloM% deepening to brown in certain places, owing apparently to 

 the volcanic element present in the limestone itself in varying quantity. 

 The debris on the steep eastern slopes is much of it very coarse and rough, 

 and very large flakes of the stone lie thickly here. 



At the extreme north-east corner a dune formation is being broken up. 

 Here are semicircular breaches of the higher dune, whence masses of very 

 loose debris come down. At the top the slope is steep and the material 

 deep and soft ; hardly any vegetation can grow, and the line separating 

 the tussock grassland from the perfectly barren space is sharp and clear. 



Possibly all parts of the basin have at one time or another been thus 

 closely covered, the covering being subsequently stripped away or buried, 

 while a certain area must always have remained sufficiently open some- 

 where in the area for the calciphile community to exist. 



Digging at a spot where several plants of Ranunculus paucifolius grew 

 close together showed that the limestone debris was here exactly 18 in. 

 deep. At that depth a more consolidated subsoil was reached. Down 

 to this depth the material was perfectly uniform, fine and incoherent, and 

 the roots of the Ranunculus, about 10 in. or 12 in. long, do not reach beyond 

 this layer, which seemed fairly damp throughout at the end of a period 

 of about a fortnight's fine weather. In a really dry season this material 

 must, of course, become extremely dry. 



Details of Distribution. 



The following are the main results of the careful search of the whole, 

 or nearly the whole, of the area, in which I had the assistance of Messrs. 

 R. Speight, A. E. Flower, and Dr. W. P. Evans. 



(1.) Most of the plants grow on the more gently sloping north-west 

 side of the basin, and are most thickly congregated on two areas, each 

 about 60 yards by 40 yards. The whole area within which all the plants 

 (except three or four) were found is about 300 yards by about 60 yards — 

 roughly, between 3^ and 4 acres. 



(2.) Nearly ail the plants were found on ground sloping at an angle 

 of from 6° to 8°. Few were found on quite level spots, and none at all 

 on very steep places. 



