Origin of the Araneidal Fauna of Yorkshire. 135 
exceedingly few of this section, the headquarters of which are 
the S.W. of Europe and the Mediterranean shores. Typical 
examples are Scotina celans Bl. taken near Huddersfield, 
Cnephalocotes curtus Sim., and Dysdera crocota C. L. Koch., 
observed at a few places on the coast (the last also, an adult 
female, in the W. Riding). They are probably the county’s most 
recent faunistic immigrants. 
In connection with the distribution of the various types, 
it is worthy of notice that some of the rarer kinds, mainly of a 
northern type, viz., Onesinda minutissima Camb., Centromerus 
arcanus Camb., C. prudens Camb., Microneta gulosa L. Koch., 
Lophocarenum mengit Sim., Caledonia cvansi1 Camb., Corni- 
cularia vigilax Bl., which elsewhere in the county occur only 
in the S.W. or very rarely in the W., are found also but in much 
less quantity in the Cleveland district in the N.E., being absent 
from the intervening areas. 
A striking feature of the Yorkshire list is the number of 
unexpected species which up to the present have been met with 
in the county. Their presence so far beyond their previously 
known limits presents problems of animal distribution, a satis- 
factory solution of which is rendered all the more difficult 
by the paucity of recorded observations, the result of the 
scanty attention which has hitherto been given to them. 
Instances have already been given of the dissemination of 
spiders by aerial flight on a large scale, but in the more restricted 
area of our own land, the same kind of dispersal periodically 
happens, although many fewer individuals take part in it. 
The most unobservant must have noticed the little black spiders 
which alight so often on their persons at certain times of the 
year, and on six occasions in the Colne Valley I have witnessed 
concurrent displays of the same character in which several 
different species participated.* One result of this power of 
flight should be the wide dispersal of the species which make use 
of it. This is really the case, for those oftenest detected in the 
act are all very common and widely distributed forms. 
With regard to four Yorkshire spiders which were new to 
Britain, Notioscopus sarcinatus Camb., Hypselistes florens 
Camb. in the North Riding, Evigone spinosa Camb. and Corni- 
cularia kochit Camb. in the East Riding (the last also in the 
North Riding and the Dee Estuary), species which do not in 
themselves exclusively favour a maritime situation, their 
occurrence on or near arms of the sea, on each of which stands 
a great port, seems to indicate that we owe their presence with 
us in some way to the operations of commerce, though it is 
possible that the first-named may have, from its now ascertained 
wider distribution in Cleveland, more claim to be considered 
* Vide The Naturalist, Feb. 1912, p. 52, and Jan. 1913, p. 83. 
1913 Mar. 1. 
