EUROPEAN ANTS IN CALIFORNIA 
217 
species must have been established in America for long periods 
past, as their range extends inland in a north-eastward direc¬ 
tion beyond the Rocky Mountains. 
Instances of specific identity in the two widely separated 
regions of California and southern Europe are to be found 
in several groups. Professor Kraepelin * reports, for example, 
that the scolopendrid Theatops erythrocephalus is such a 
case. From California it has spread as far as Oregon. 
In southern Europe it is known from Portugal, Italy, 
Dalmatia and Hungary. The genus Theatops is confined to 
North America, including the Sandwich islands, and southern 
Europe. 
A member of the order Palpigradi, a minute creature 
somewhat resembling a scorpion in shape, has been observed 
in Texas and named Koenenia wheeleri after Professor 
Wheeler. Two other members of the genus are known from 
South America, one from Chile, the other from Paraguay. 
But the nearest relations of the North American form are evi¬ 
dently Koenenia mirabilis of Sicily and Tunis, and K. draco of 
the Balearic islands. The only two other species live in Siam.f 
We thus have in this ancient group again the same intimate 
affinity between southern Europe and south-western North 
America as in some ants, beetles and butterflies, showing 
clearly that the same potent cause, which is certainly not acci¬ 
dental distribution, has contributed to bring it about. In 
order, however, to make quite sure that these are genuine 
instances of migration on a land surface, and not due to 
occasional or accidental transport, let us now examine care¬ 
fully the range of a large fresh-water form and endeavour to 
trace its origin. 
Fresh-water crayfishes, as Dr. Ortmann remarks in his 
excellent account of them, do not possess any exceptional 
means of dispersal. They are restricted to fresh water and 
cannot exist out of it, neither in salt water nor on land. 
Moreover, they do not possess, during any stage of their life 
history, means or devices which might favour their passive 
transport from one fresh-water system to another. The whole 
character of their range is opposed to the assumption that 
* Kraepelin, K., “ Revision der Scolopendriden,” pp. 64—66. 
t Hansen, H. J., “On Koenenia.” 
