INTRODUCTION. Vii 
Oriental and Australian Regions, and New Zealand. But most significant is the fact 
that two genera, Jschnothele and Evagrus, both strongly represented in Central 
America, are found also in Madagascar and South Africa. 
The Ctenizine, a subfamily of the Ctenizide, are found in the Southern States of 
North America, Central America, the northern districts of South America, the Antilles, 
the Mediterranean Region, Central Asia, Burmah, South China, and the Japanese 
Islands, as well as in New Guinea and some of the Polynesian Islands. 
The Avicularie, of the family Theraphoside, are present throughout the Gulf States 
of North America, Central America and the Antilles, the whole of South America, the 
western districts of Ethiopia, the Mediterranean Region, India, and Burmah. 
Amongst the Argyopide, the genus Nephila may have originated in the Oriental 
Region. Its western representative, however, is very widely distributed in the New 
World. There has been found, moreover, in the Florissant deposits of North 
America a fossil species of Nephila which is probably identical with the existing 
form mentioned above. If so, this would point to the vast time required in the 
differentiation of species, though naturally there would be great variation in this 
respect. 
The genus Filistata, of the family Filistatide, is common to North, Central, and 
South America, the Antilles, Africa, and the Oriental Region. The members of this 
family possibly originated in the Ethiopian Region and spread westwards. 
To take, now, a case where it is not improbable that the reverse has happened, 
we find numerous species and allied genera of the family Anyphenide in North and 
Central America, while but three or four species of one genus, Anyphena, are found in 
the Palearctic Region. The ancestors of these may have passed across from the parent 
stock before the Behring Sea bridge was broken down, and established themselves 
there during Oligocene times ; for they are found in the beds of this period, in both 
Europe and North America. It has been well pointed out by Mr. R. I. Pocock * that 
this case is remarkably similar to that of the mammalian family Camelide, of which 
a number of genera existed in North America in Tertiary times, passed subsequently 
* Proc. Zool. Soc. Lond. 1903, 1. p. 367. 
