216 JR. 1. POCOCK [march 



The Uropygi were represented by the genus Geralinura, which 

 apparently differed but little from the existing Thelyphonidae, and has 

 been found both in Europe (Bohemia) and in North America (Illinois). 

 The fossil forms, which seem to me to be referable to the Amblypygi, 

 have been named Graeophonus and Gera/phrynus, 1 the former being 

 based upon remains from the Carboniferous beds of Cape Breton in 

 Nova Scotia, the latter from those of Illinois. But from Palaeozoic 

 times down to our own day the past history of the Pedipalpi is an 

 absolute blank. 2 Nor is our knowledge of fossil scorpions much more 

 complete. Although several genera and species have been described 

 from Upper Silurian and Carboniferous bed*, both in North America 

 and Europe, only one species has been recorded as existing during the 

 immense period of time that has elapsed since the Palaeozoic epoch. 

 This was obtained in the oligocene amber beds of the Baltic. 



Nevertheless, scanty as are these data, they afford support to the 

 view that these Arachnida originated in, and were widely distributed 

 throughout, the northern hemisphere. 



In attempting to establish geographical areas based upon a study 

 of these Arachnids, one important consideration must be borne in mind, 

 namely, that we are dealing with organisms which are wonderfully 

 specialised in particular directions and highly conservative in 

 structural characters. The scorpions, in fact, furnish a famous example 

 of a persistent type of life, and in this particular they do not surpass 

 the Pedipalpi of the family Thelyphonidae. Considering the wonderful 

 changes that have affected the northern hemisphere since Palaeozoic 

 times, it is astonishing that these Arachnids have varied so little. To 

 many zoologists the characters upon which the orders are divided into 

 families, genera, and species may seem of small importance as compared 

 with those of such highly plastic animals as the Mammalia ; but 

 keeping in view the fixity of their characters as a whole, it seems clear 

 that what is regarded as a specific or generic difference between two 

 forms may represent a period of separation sufficiently long or a change 

 of environment sufficiently great to produce differences of far higher 

 systematic value in more plastic organisms. Consequently a generic 



1 Described by Mr. Scudder. This is no place to attempt a detailed criticism of this 

 author's work on fossil Arachnida. The expenditure of a little trouble in gaining an 

 acquaintance with the morphology and classification of recent forms would have given his 

 monograph a value to which at present it can lay no claim. Without an examination of 

 the fossils, one's criticisms are, more or less, guess-work, but, judging from the figures, it 

 appears to me that Mr. Scudder has, in more than one instance, mistaken the ventral for the 

 dorsal aspect of his specimens, has referred to the same species specimens presenting 

 characters probably of generic importance, and has placed in the same order, Anthracomarti, 

 representatives of the existing orders of Aianeae, Opiliones, and Pedipalpi. The genus 

 Graeophonus, which is almost certainly an Amblypygous Pedipalp, he places in the family 

 Geralimuidae, alongside of Geralinura, an unmistakable Uropygous form. 



2 The so-called Tertiary Phrynus from the Oligocene beds of Aix, cited in works on 

 Palaeontology, and described ten years ago by Gourret as Phrynus marioni, is not a 

 Phrynus (Pedipalp), as a glance at the figure will show, but a spider allied to the 

 Carboniferous Arthrolycosa and the existing Liphistius. 



