" WIND-SCORPIONSr 327 



The two forms which have been most dihgently studied 

 in the past have been, as above noted, the Spiders 

 and the Scorpions, with some reference to the large Pedi- 

 palpi. The Book-scorpions and the Mites, being smaller 

 forms, have been left somewhat on one side, while the very- 

 important claims of the Galeodidse to a voice in settling the 

 family tree of the Arachnida, although long ago put forward, 

 are only now beginning to be closely examined. 



Here, then, is another inducement to collectors and 

 naturalists, not only to make good the deficiencies in our 

 museum collections but also to supply material to our 

 laboratories ; for the morphological interest centring in the 

 Galeodida; is as great, if not greater, than the biological. 



I propose, then, as briefly as possible, to describe com- 

 paratively some of the special features of the Galeodidse, in 

 order to show how near they take us to a reconstruction of 

 an ancestral form capable of producing all the known 

 Arachnids. 



In all segmented animals, no matter what theory we 

 adopt as to the origin of metamerism, we are justified in 

 assuming that that form which shows the segmented condi- 

 tion least modified and obscured by fusions and distortions 

 of segments remains in this respect nearest the common 

 ancestor of its class. Few animal groups show such a 

 marvellous variety of modifications of the primitive seg- 

 mentation as the Arachnids. Each family has its own 

 distinct methods and degrees of fusion, and what is most 

 remarkable is that these different fusions seem to be dis- 

 tinct from one another. This is very important because it 

 appears unmistakably to prove, what we have already 

 suggested above, that all the Arachnidan families are 

 distinct specialisations of some primitive form, i.e., they 

 cannot be deduced from one another. 



These different fusions are worth noting and comparing. 

 Galeodes has the first three segments fused and all the rest 

 free ; the sixth and seventh, however, are modified by the 

 constriction between them being drawn in to form a 

 waist. Behind the waist all the ten segments are swelled 

 up to form a bag-like abdomen capable of enormous ex- 



