us 



ARTIIROPODA. 



next four segments bear spiracles which lead to four pairs of lung 

 sacs. The heart is abdominal and the ' liver ' diverticula are con- 

 fined to the same region. The large number of abdominal ganglia 

 distinct from the oesophageal ring is also characteristic. From 

 three to six pairs of eyes occur. 



The scorpions are inhabitants of warm regions, ranging north with us 

 to the Carolinas and Nebrasl^a. JBiifJius* Centrurus* 



Order II. Phrynoidea (Pedipalpi, Thelyphonida). 



The thoracic segments are fused, and of the appendages only 

 the last three are walking feet, the third pair having the last 

 joint (tarsus) developed into a long many-jointed tactile flagel- 



FiG. 462.— yV(i-f/?nfs (-P/n-^H/c/iu.s') rentfuriiu's. iFrom Schmarda.) 



lum. The cheliceras arc strong and sp)ined, but end in a claw, not 

 in a pincer. The cheliceras are also clawed and are possibly poison 

 organs, since the bite of these animals is feared. The abdomen 

 consists of eleven or twelve somites and contains two pairs of lungs. 

 There arc eight eyes — two large ones in the middle of the cephalo- 

 thorax, and three small ones on either side. 



The species are tropicab PTtrijniis (fig. 4C0) lias a simple abdomen ; 

 Tlielijphomis* (fig. 405, D) has a short postabdomeu which bears a long, 

 many-jointed thread. One species in the southwestern United States. 



Order III. Microthelyphonida. 

 Small animals as yet known only from Texas. Sicily, Paraguay, 

 and Siam. They have a general resemldance to a scorpion, the 

 clielicorfB are three-jointed and cbolate, the pedipalpi simple, neither 

 tliese nor any of the legs having chewing lameUai. The head is 

 distinct from two 'thoracic segments," the abdomen is eleven- 

 jointed and is terminated by a long many-jointed oatidal tlagellum. 



