1912. | S. Kemp: Notes on Decapoda. 11g 
great central sea now represented by the N. Atlantic and the 
Mediterranean, there existed a ‘ Sino-Australian continent. This 
involved Eastern Asia, the Indo-Malaysian Archipelago and 
Australia, extending southwards to the Antarctic regions and 
from it a tongue of land reached out to New Zealand by way of 
New Guinea and Norfolk Island. During Upper Cretaceous times 
the ‘ Sino-Australian ’ continent was divided by a neck of water 
extending across the region now occupied by Sumatra and Celebes 
and the land extension from Madagascar to S. India reached north 
to the northern or Asiatic part of that continent. In Lower and 
Upper Tertiary times New Zealand was completely isolated as it 
remains at the present day ; in the former period India was merely 
an island, an eastern sea-connection between the ‘ Mediterranean ’ 
and Indo-Pacific extending across Assam and Burma, while in the 
latter it approaches the shape which it at present bears. 
On these theories the explanation of the discontinuous distri- 
bution of X. curvirostris is possible, though it can hardly be said to 
be very convincing. Wemust assume that Xiphocaridina curviros- 
ivts evolved from some unknown marine or freshwater ancestor in 
early Cretaceous or pre-Cretaceous times and remained unchanged 
until the present day. In the Lower Cretaceous period it would 
have opportunities of spreading to New Zealand on the one hand 
and to Lower Burma on the other. Subsequently, while becoming 
isolated in New Zealand it must have persisted in Burma or in the 
country existing to the west of it until Assam reappeared during 
the Upper Tertiary period. 
The existence of Xiphocaridina compressa both in China and 
Japan and in Australia seems to show that this species also, 
according to Ortmann’s theories, must have remained with- 
out sensible modification for almost as long a period. Every 
zoologist will readily call to mind other instances tending to a 
similar conclusion. 
Although no exactly parallel case of geographical distribution 
seems to be known among freshwater Crustacea, the Megascolecid 
Oligochaeta of the sub-family Octochaetinae afford an instance of 
a closely similar nature. According to Michaelsen (1909) this sub- 
family is found only in India and New Zealand ! and although no 
species appear to be common to the two, two genera, Octochaetus 
and Hoplochaetella, occur in both localities. 
Michaelsen holds that the only possible interpretation of these 
facts is that at one period a direct land connection existed be- 
tween India and New Zealand. He remarks (p. 203): ‘‘ I need not 
explain to any zoo-geographer that the discontinuation of these 
two regions of distribution in the Octochaetinae is quite a com- 
mon matter in geographical distribution, the two regions, New 
Zealand and India, perhaps together with a third region, Mada- 
gascar, the home of Howascolex, representing the peripheral parts 
! Michaelsen mentions that another genus, Howascolex, known only from 
Madagascar, might perhaps also be regarded as a member of this sub-family. 
