" WIND-SCORPIONSr 329 



while the Spiders have all the segments fused into two com- 

 pact groups joined together by a waist. 



On analysing and comparing these different fusions 

 and modifications of segments, we find three features 

 common to them all. In all at least the first three seg- 

 ments are fused together, and in all there is some trace of 

 a waist between the sixth and seventh segments, and in 

 all the segments immediately behind the waist are capable 

 of distention. In these facts we may therefore find some 

 indication as to what the common ancestral Arachnid was 

 like. 



Hitherto, discussions of affinities based upon segmenta- 

 tion have dealt almost entirely with the number of seg- 

 ments. Most of my own work with Arthropods has gone 

 to show that, important as are the fusions of segments 

 treated quantitatively, that is not enough. The segmenta- 

 tion must be studied and compared qualitatively. It is 

 not enough to ascertain merely how many segments are in- 

 corporated in each fused area, we must also ascertain how they 

 have been fused together, that is, how distorted in the pro- 

 cess, and, where possible, why they were so modified. Some 

 idea of the importance of this qualitative study of segments 

 will be gathered in the following pages. 



Now the fact that the Galeodidse have, alone among 

 Arachnids, retained the primitive number of fused segments, 

 would lead us to expect that they would also show the 

 qualitative nature of this fusion more clearly than any other 

 Arachnid. And this is indeed the case. Careful examina- 

 tion of the relative character and position of the limbs and 

 mouth, compared with what we know of the nature of the 

 food, shows that this primitive fusion and distortion of the 

 segments must have been brought about as an adaptation 

 to a special manner of feeding. What this method of 

 feeding is, we have already described : the first pair of 

 limbs are thrown forward on each side of and above the 

 anteriorly placed mouth ; they seize and crush the prey, the 

 blood of which is then sucked out. 



If now we can further show that the ancestral Arachnid 

 fed in the main as Galeodes feeds, we should then have 



