Coxal glands of the Arachnids. 255 



41 a), but on the other side of the same specimen Uie coUectio]? 

 tubule is closed by a bulge ( B) from the wall of the labyrinth sac 

 (photo 42, 42 a) the bulge protruding also into the lumen of the 

 saccule (photo 46 is a Compound of 41 and 42). 



It appears that the muscle fibres of the saccule on this side 

 are contracted, and in pulling out the walls of the saccule a partial 

 vacuum is temporarily formed in its lumen, and the labyrinth sac, 

 which suiTounds the collecting tubule, closes up over it; forming a 

 valve which prevents any back flow through the tubule from the 

 labyrinth sac, thus allowing the saccule to All up again with fluid 

 from the hemocoele outside. As the muscles become relaxed the 

 tubule opens again and fluid is forced from the saccule into the 

 labyrinth. 



In connection with the saccule, it may further be remarked that 

 the tissue composing it varies much in dilferent genera (compare 

 photos 34, 34 a and 34 b). In Paragaleodes (34) it is very loose and 

 porous; less so in Solpuga (34 a) and in Galeodes (34 b) relatively 

 compact and dense. The tissues surrounding the saccule also show 

 the same progressive condensation. Finally in the specimen Galeodes 

 sp.? not only is the tissue of the saccule very compact, but the 

 special muscles {3IS) appear to be wanting, so that it is doubtful 

 if there can be any pumping action.^) 



The collecting tubule is usually long and narrow, lined with 

 epithelium diftering from that of the labyrinth sac on the one band 

 and from the cells of the saccule on the other, but in the specimen 

 of a Galeodes just mentioned, the collecting tubule appears to be 

 lost as a separate entity, and the change from the cells of the 

 saccule to the columnar cells of the labyrinth is abrupt as is shown 

 in photograph 45, but the collecting tubule is in the usual place 

 between two pouches of the labyrinth sac. It may be that the loss 

 of the pump and the alteration in the character of the collecting 

 tubule have some connection with each other. 



In this specimen also the columnar cells of the labyrinth sac 

 {SL) are much more regularly disposed than in any other examined, 

 and the columnar character is even retained in the cells of the 



1) I am now inclined to think that this specimen belongs to the 

 genus Othocs of the Galcodidae (Nov. gen. HiRST 1910). In its internal 

 Organisation it differs considerably both from Galeodes and Paragaleodes^ 

 yet Stands nearer to them than to the Solpugids. 



