//. ACBEATA: AGAIilNA. 453 



liiiider pair are replaced by trachea?, which may open by separate spiracles 

 (Tetrasticta) or by a comnion opening (Tristicta, fig. 460). 



Sub Order I. TETEAPNEUMONES. Four lungs, four spinnents and 

 eight eyes in two rows. The MYGALlD^are the most important group, large 

 forms \Yhich spring upon their prey, capturing even small bird's and'mic^?. 

 To the genus J/y,r/«?e* belong the spiders (commonly but erroneously called 

 tarantulas) which occur in banana bunches. Here also belong the trap- 

 door spiders, Cteniza* ot the southwest, which e.xcavate burrows in the 



I-~]G. ilX.—Ct^'niza ccernfiiiaria in its tube, closiTii;; the lid. a, eyes; f>, inside nf lid 

 with places fur the claws; c,eg^' cocoon. 



soil, lino them with silk, and close them with a hinged lid (fig. 471). 



Sub Order II. DIPXEUMOXE.'-;. One pair of lungs, one of trachea; 

 si.x spinnerets. Here belong most of the native and numerous tropical 

 species. Sunie (VAGABUND^E) use their webs only to line the nests and 

 enclose the eggs, which are either hidden away or carried about attached to 

 the body, while they spring upon or chase their prey. SEDENTARIA are 

 the web builders, their webs varying widely in structure. Of the first 

 group the Saltigrada include forms which jump upon their prey (Attas* 

 F/iidippux,* Hah voce nt nun'*), and the Citigrada {Lijcosa,''- Doloinedes,* 

 Trochosri *j, which run their prey down. Among these is the true Taran- 

 liila, T. i(/)i(lke of Italy, wliose Ijite was once believed to cause a frenzy only 

 to be cured by peculiar music (' Tarantello'). The Sedentaria are divided 

 according to the web-building habits- The Orbitelarle or orb weavers 

 { f-Jjii-ii-ii,* Ari/iopi'*) form vertical webs which in many instances are com- 

 [ilete circles. The Retitelarle {T/ieriJiiiiii,'-'- £'/7'r/o?if *j build irregular 

 webs. The species of Lntrodectes * are reputed poisonous to man (fig. 

 4r,S). The TUBITELARLE build horizontal webs with a tube to the mar- 

 gin in which they lay in wait for insects. 



Order II. Acarina. 



The mites, parl:ly from parasitism, partly from other conditions 

 of life, have become, in some instances, considerably modified. 

 Witli the fusion of ceplialothorax and abdomen the last traces of 

 scji'mentation in the body are lost. Yet they retain the six jjairs 

 of appendages — four pairs of legs which at once distinguish them 

 from tlie parasitic hexapods; and two pairs of mouth jDarts, modi- 

 fied into a suclciiis; beak. This consists of a tube formed by the 



