278 MANUAL OF NATURAL HISTORY. 



7. Family. — Water-Ticks (Hydrachnidse). Palpi 



with the last joint armed with points, th® 

 third and fourth joints larger than the others-; 

 body simple, oval or rounded ; eyes supero- 

 anterior ; legs ciliated, formed for swimming ; 

 parasitic in the young state. Aquatic. 



8. Family. — Harvest-Ticks (Leptidse). Palpi short; 



sucker porrected ; body depressed, coriaceous,, 

 ovately rotund ; legs six, two being unde- 

 veloped. 



II. ORDER — Jointed-Trachearians 

 (Adelarthrosomata). 



Body divided into three or four distinct segments; 

 abdomen distinct, annulated ; mouth with conspi- 

 cuous didactyle pincers or chelicerse, 



1. Famiy. — False-Scorpions (Solpugidae). Mandibles 



in the form of large compressed claws, with a 

 moveable finger ; palpi large, in the form of 

 feet or of cheliferous arms ; body oblong, soft ; 

 abdomen hairy. 



2. Famiy. — Book-Scorpions (Cheliferidse). Man- 



dibles short, didactyle at the ends ; palpi 

 very large, arm-like, with a pincer at the 

 end ; body ovate, depressed, narrowed in 

 front ; legs of equal size, short, ending in two 

 hooks. 



3. Family. — Shepherd-Spiders (Phalangidse). Man- 



dibles very conspicuous, composed of two or 

 three pieces, free, ending in a didactyle pin- 

 cer ; palpi filiform, ending in a hook ; body 



