I B. H. BUXTON 



bladder (5) , a short exit tubule lined with cells derived from the 

 hypodermis leads to (6) the outlet^ on the external surface, 

 either on segments III or V, or on both of these segments, 

 just posterior to the appendage. 



In Group II the same arrangement holds good except that 

 between the collecting tubule and the labyrinth there is a large 

 sac lined with secretory epithelium, and the outlet is on segment 

 II. 



It was pointed out in the pre\ious article that the coxal 

 glands of Group I appear to be homologous with the large ne- 

 phridia on segments VI and VII of Peripatus, whereas the coxal 

 glands of Group II show homology with the salivary gland of 

 Peripatus, the outlet of which is situated on segment II. 



GROUP I. I. SCORPIONS AND SPIDERS 



Several genera, both of scorpions and of Theraphosid spiders 

 from the East Indies, have been recently examined, but there 

 is nothing further to add to the description which has already 

 been published of the coxal glands of certain American, Euro- 

 pean and African genera. 



It may be recalled that the coxal gland of the scorpions lies 

 m segments V and VI with an outlet at the base of the posterior 

 surface of appendage V. 



The coxal glands of the spiders show considerable differences. 

 That of the Theraphosid spiders has two saccules and two 

 outlets, one of each on segment III and the other on segment 

 V with a large and complicated labyrinth apparently common 

 to both saccules and outlets. The Araneae verae have lost 

 the coxal gland of segment V, retaining only that of segment 

 III; and, with the exception of the six-ej^ed spiders, the Sica- 

 riids and Dysderids (to which can now be added the Oonopids), 

 the coxal glands of the higher spiders show various stages of 

 degeneration, or perhaps simplification. 



^ There is always an outlet on the external surface, both in immature and 

 adult specimens. The arrangement of special muscle fibers around the exit 

 tubule indicates that it can be closed or opened at will. 



