'' wind-scorpions:' 339 



the bases of which in the primitive and more soft-skinned 

 ancestor the bristles grew. The material which originally 

 formed a bristle may be supposed to have been retained in 

 a modified and fluid form within the sac which, in its turn, 

 grew larger and larger to form the highly specialised poison 

 or spinning glands of the modern Arachnids. I feel sure 

 that an exhaustive comparative study of the bristles and 

 glands of the Arachnida would completely establish this. 



Let us then briefly sum up the characters which we can 

 safely attribute to the ancestral Arachnid as soon as the 

 evidence of the Galeodidse is added to and compared with 

 that obtainable from the other Arachnids. 



We must picture to ourselves a loosely segmented 

 hairy creature showing a slight waist-like constriction 

 between the sixth and seventh segments. The first three 

 segments are fused together and distorted in such a way 

 as to range two pairs of limbs round an anterior mouth 

 which is at the tip of a kind of beak. These limbs are 

 specialised for seizing prey and crushing it in front of the 

 mouth. The four following pairs of limbs are used for 

 locomotion, while those of the segments behind the waist 

 which are often swelled up by liquid food are more or less 

 useless and degenerating. This, in brief, would represent 

 the form from which, by modification and specialisation in 

 various directions, all the existing Arachnida could be 

 derived. 



Havine now reconstructed an ancestral form for the 

 Arachnida, we ought with its help to be able to answer 

 some of the questions relating to the probable affinities of 

 the Arachnida to the Insecta and to the Crustacea. A few 

 words on this subject will still further emphasise the utility 

 of the analytical method here advocated and adopted. 



It is now almost universally admitted that all the differ- 

 ent Arthropods are to be deduced from Chsetopod Annelids. 

 A question still to be decided, however, is, are they dis- 

 tinct and separate modifications, or have they branched off 

 from one another, starting from some original Arthropod 

 which linked them all with the Annelid ? Many have been 

 the proposed lines of descent of the Arthropods from some 



