392 



ARTHROPODA 



glands. It is the 'sting' of the animal wliieh causes painful wounds in 

 man, and in the large tropical species is, perhaps, fatal. Usually scorpions 

 feed upon insects, wliich they seize with the pincers and kill witli the sting. 

 On the ventral surface of the second abdominal somite (fig. 421) are a 

 pair of appendages, tire combs or pcctiin-s, rods with teeth on one side, of 

 uncertain function. They are clearly appendages with modified gill 

 leaves, and from their nearness to the sexual opening and their rich nerve 

 supplv are supposed to be stimulaliiig organs in copulation. The next 

 four segments bear spiracles which lead to four pairs of lung sacs. The 



Fig. 422. — Tlielvfilioiuis cauJj.'iis. i, clicliccra; 2, pcilipalpi; :;, HagoUate third leg; 

 4-0, walking feet. IScloWj clicliccra enlarged. 



heart is alidominal and the liver diverticula are contined to the same 

 region. The large numlier of abdominal ganglia distinct from the 

 oesophageal ring is also characteristic. From three to six pairs of eyes 

 occur. 



The scorpions are iiihaliilants of wiirni regions, ranging north with us to the 

 Carolinas and Nebraska. Biilliiis,''' Cciilrurus.''' 



Order II. Phrynoidea (Pedipalpi, Thelyphonida). 



The thoracic segments are fused, and of the appendages only the last three 

 arc walking feet, the third pair having the last joint (tarsus) de\eloped into a 

 long many-jointed tactile llagellum. The clielieer:c are strong and spined, but 

 end in a pincer in some species. The chelieera; are also clawed and are jiossibly 

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



