140 THE ZOOLOGIST. 
an isolated one. The case is almost an exact parallel to that of 
Totanus incanus and T. brevipes, and it is worthy of note that 
in both cases the New World species is the one which has what 
is generally regarded as the older form of tarsus (i. e., reticulated 
instead of scutellated), but in the Curlew this character is 
normal, whilst in the Sandpiper it is exceptional. 
The geographical distribution of the species belonging to the 
genus Numenius is very interesting, and presents a remarkable 
similarity to that of the species composing the genus Hematopus. 
In many respects the habits of the Curlews resemble those of 
the Oystercatchers ; both groups of birds are principally shore- 
feeders, and both are occasionally found on the banks of great 
rivers. The Curlews undoubtedly breed further inland, but the 
lines of migration of both groups appear to be similar, and it is 
not improbable, as will hereafter be shown, that they started 
from a common centre, and may have even migrated in company. 
In both genera the species may be ranged in four or five groups, 
apparently originating in the relation caused by their having 
chosen different coast lines leading from the Polar basin. 
The species belonging to the genus Numenius may be naturally 
divided into five groups, as follows :— 
Lower back much paler = 
than mantle 1 B 
Crown plain brown, with a 
more or less distinct pale 
: ¢ i mesial line. 
Primaries and second et ] 
nearly uniform brown 
a) 
Assuming that the ancestors of the genus were originally 
inhabitants of the Polar basin, let us first ascertain the probable 
routes which they would take to escape from the gradually 
accumulating Arctic ice, and, secondly, what evidence, if any, 
can be found of the origin of each group. 
We may picture to ourselves the ancestors of the species now 
placed in the genus Numenius living in the temperate region of 
the Polar basin, with other shore birds, during the series of inter- 
glacial years, immediately succeeding the Glacial Period which 
isolated and differentiated them into species, these species being 
