ON THE SPINNING ORGANS AND ARCHITECTURE 

 OF EVAGRUS, A THERAPHOSID ARANEAD.^ 



C. W. STEVENSON. 



The most important work on the spinning glands of spiders is 

 thatof Apstein (1892), who distinguished the five following kinds : 



1. Aciiiifor)n Glands. — Oval-shaped glands with long duct; 

 gland consists of tunica propria and epithelium, which stains 

 evenly in all parts, duct of which bears no epithelium and ends 

 on a spool with long spinning hair. 



2. Piriform Glands. — Pear-shaped glands consisting of tunica 

 propria and epithelium, the lower portion of which stains deeper 

 than upper portion ; the duct bears a thick tunica intima and ends 

 on a short thick spool, with thick spinning hair. 



3. Ampullaceoiis Glands. — Sac-like glands consisting of tunica 

 propria and epithelium, of which the upper portion is cylindrical, 

 then has a sac-like swelling from which the duct consisting of 

 tunica propria, epithelium and tunica intima forms a double loop, 

 the three branches of which are formed in a tunica propria, and 

 ends on a large truncate spinning spool. 



4. Tnbuliforui Glands. — Cylindrical glands consisting of tunica 

 propria and epithelium, duct consists of tunica propria, epithelium 

 and tunica intima and ends on a large spool. 



5. Aggregate Glands. — Aboraceous glands of tunica propria 

 and epithelium, with wide ramifying lumen of which the duct, con- 

 sisting of tunica propria, epithelium and tunica intima bears pro- 

 tuberances and ends on a large spool with long pointed spinning 

 hair. 



Apstein gives only a short description of one of the Thera- 

 phosids, Lasidora Erichsonii, of the family Aviculariidse. He found 

 in these only piriform glands, of which the spinning hairs were 

 ringed or annulated. 



The only subsequent work is that of Warburton (1890) on 

 Argiopids; McCook(i890)on Epeirids ; Borgert's (1890) general 



^ Contributions from the Zoological Laboratory of the University of Texas, No. 92. 



105 



