xin COXAL AND POISON GLANDS 337 



The COXAL GLANDS fire two elongated brownish-yellow 1 indies, 

 situated beneath the lateral diverticula of the stomach, and 

 between it and the endosternite. They present four slight pro- 

 tuberances which project a short distance into the coxae of the 

 legs. The glands appear to be ductless, but their function is 

 thought to be excretory. They were first observed in the 

 Theraphosae. 



All Spiders possess a pair of POISON-GLANDS, connected by a 

 narrow duct with a small opening near the extremity of the fang 

 of the chelicerae. The glands are sac-like bodies, usually situated 

 in the cephalothorax, but sometimes partially (Cl-nlnnm} or even 

 entirely (Mygale] in the patura, or basal joints of the chelicerae. 

 Each sac has a thin outer layer of spirally-arranged muscular 

 and connective tissue fibres, and a deep inner epithelial layer of 

 glandular cells. The cavity of the gland acts as a reservoir for 

 the fluid it secretes. The virulence of the poison secreted by 

 these glands has been the subject of much discussion, and the 

 most diverse opinions have been held with regard to it. The 

 matter is again referred to on p. 360. 



VOL. IV 



