82 INVEKTEBRATE ANIMALS. 



stituents. If the segregation be natural, i. e. if the 

 genealogical affinity be real and close, great indeed must 

 have been the influence of habits and circumstances' 

 under which a Galeodes and a Desmodex, a Hydrachna, 

 a Chelifer and a Pycnogonum have been evolved from a 

 common and not very remote ancestor. 



Sub-Class ARACHNIDA-PULMONARIA. 



Eespiration by pulmonary sacs, vi'ith or without respira- 

 tory tubes ; cephalothorax more or less distinct from 

 the abdomen ; eyes six, eight, or twelve in number. 



Group 195. -Order PEDIPALPI. Scorpions and allies. 

 Head and thorax amalgamated ; abdomen distinctly 

 segmented. Estimated number of species, 93 (Walck- 

 enaer). 



^ Examples of about 22 species of Scorpions, 

 including the Black or Rock-scorpion of Africa, 

 the most formidable of the family. Several 

 species of Pkrynus : observe in the largest 

 example, which is probably of an undescribed 

 species, the extreme length and slenderuess of 

 the many-jointed tarsi of the first pair of legs. 

 Examples of Thelyphonus, a hateful-looking 

 but probably not venomous animal, of which 

 species are found in Mexico, Brazil, India, 

 Java, and other hot countries. 



Group 196.— Order ARANEIDA. Spiders. Head and tho- 

 rax amalgamated ; abdomen not segmented ; eyes six or 

 generally eight. The life history of spiders is deeply 

 interesting ; that of the British species has been well 

 told by Mr. E. F. Staveley. 



