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B. H. BUXTON 



The coxal glands of the Arachnids have always been described 

 as being located in such and such a segment, but it is probable 

 that fundamentally each coxal gland represents two segments 

 instead of one. There seems little doubt that in the saccule 

 we have the last traces of the coelom, which would belong to 

 the segment anterior to that of the main part of the coxal gland. 

 One may reflect that in the worms the coelom of one segment is 

 connected with the segment next posteriorly to it by means of a 

 funnel represented by the collecting tubule of the arachnids. 

 The funnel leads through the partition into a coiled nephridium 

 situated in the next segment ; the coiled tubule of the nephridium 



Diagram 4 Four segments of a worm, showing the nephridia. 



having an outlet near the anterior partition of the segment 

 (diagram 4). When, therefore, dealing with the arachnids, we 

 say, as for instance with Phrynicus, that the saccule lies in seg- 

 ment III and the gland has its outlet on segment III just behind 

 appendage III, it should be borne in mind that the saccule and 

 collecting duct represent the coelom and funnel of segment III, 

 while the labyrinth and outlet belong in reality to segment IV ; 

 the labyrinth having encroached upon and suppressed the coxal 

 glands immediately posterior to itself — a process of encroach- 

 ment which is still in progress in the Charontini, the small pos- 

 terior gland of which is composed of the coelom and funnel of 

 segment V and the nephridium of segment VI. 



