RIVER 'TERRACES, Bis 
previously deposited, and we should have a series of alluvial terraces, 
such as we see in New Zealand. Alluvial terraces can, therefore, only 
be formed during a period of elevation succeeding a period of subsi- 
dence, and the size of the terraces will be proportional to the amount 
of these movements. 
This explains why in different countries we see different kinds of 
terraces or sometimes none at all. It is because different countries 
have been subjected to different vertical movements. We must re- 
member that rivers are very old. Older indeed than the mountains 
which they drain; for it is the rivers that have carved out the moun- 
tains. As the land gradually rose from the sea the rain and rivers 
commenced their work of erosion and cut, what without them would 
have been a plateau, first into a series of hills and ultimately, if the 
land rose sufficiently high, into a chain of mountains. Now the New 
Zealand Alps were probably formed about the close of the Jurassic 
period and have never since been submerged. Consequently, the 
rivers that drain them are, in the upper part of their courses, of pre- 
cretaceous age. They have seen many vicissitudes of elevation and 
depression; but it appears that the last subsidence in pliocene times, 
and the subsequent re-elevation, are the causes of the remarkable 
series of terraces that we now see in New Zealand. 
CORRESPONDENCE. 
SPECIES OF PSHEPHOLAX. 
To the Editor. 
Sir,—Referring to my communication of March 12th, 1884, on 
the identity of the two weevils Psepholax coronatus and P. tibialis, 
I have been informed by Capt. Broun that the insect proved by me to 
be the female of P. coronatus is not P. tibialis but a distinct species 
differing structurally from that insect. Capt. Broun encloses the 
following. description of the two insects, which he requests me to 
forward you :— 
“‘ Psepholax coronatus, male.—Oblong-oval convex, slightly nitid- 
piceous, antenne and tarsi rufopiceous, clothed with greyish scales 
which form two broad lines on the thorax. Rostrum broadly impressed 
in front with an inter-antennal groove, much more finely and distantly 
punctured than the head. Thorax rather closely punctured, with a 
smooth dorsal space. Elytra striate, interstices with the usual rugose 
asperities but without spines and bearing erect setiform scales. Tibi 
almost straight the intermediate with a dentiform projection on the 
middle. Length, (rost. excl.), 33; breadth, 2 lines. 
““ Psepholax tibialis differs structurally. ‘The middle and hind 
tibiz are strongly arched and peculiarly twisted and do not bear projec- 
tions on the middle nor at the outer extremity. The sculpture of the 
elytra is different ; the strie are deep and narrow, the interstices when 
