THE SCORPIONS. 



161 



Family 1. SCORPIONIDJE. 



2. PHUYNIDJE. 



the membranous lung-sacs ; some zoologists also believe that inspiration is caused by a similar 

 agency. The true tracheae, when present, are analogous to those of the Insects and Myriopods, open 

 like them by stigmata, and ramify throughout the body. 



The great diversity of organisation presented by the members of this order renders their division 

 into families exceedingly clear and distinct, and we may recognise with facility the following five 

 groups : 



I. Respiration by lung-sacs (Pedipalpi). 



a. Maxillary palpi with nippers ; stigmata four pairs ; terminal 

 segments of abdomen forming a slender tail, with a sting at 

 the end ........ 



b. Maxillary palpi with imperfect nippers, or simple ; two pairs of 



stigmata ; no caudal sting ...... 



II. Respiration by tracheae (Adelartkrosomata). 



a. Cephalothorax not segmented : 



* Maxillary palpi with nippers ..... 3. CHELIFERIDJE. 



t Maxillary palpi simple ..... 4. PHALAXGIID^E. 



b. Cephalothorax divided into four segments .... 5. SOLPUGIDJE. 



FAMILY I. SCORPIOXID-E. 



The species of this family are exceedingly uniform in their structure. They consist of a rather 

 broad anterior part, composed of the Cephalothorax and seven distinct segments following it, at the 

 hinder extremity of which come five narrower segments forming a sort of tail, terminated by a 

 bulbous piece having 

 a short but sharp 

 point. At the front 

 we see a pair of 

 jointed organs having 

 regular nippers, like 

 the so-called claws of 

 a Crab or Lobster, 

 and behind these four 

 pairs of ambulatory 

 limbs. The type is 

 so interesting and irn- 

 portant,however, that 

 we must describe its 

 structure a little more 

 particularly. 



The upper sur- 

 face of the cephalo- 

 thorax is covered by 

 a shield-like horny 

 plate, upon which 

 from three to six 

 pairs of simple eyes 

 are to be seen, a pair of 



extra size being placed ANDROCTOXUS (OR SCORPIO) OCCITAXUS. 



close to the middle 



line of the shield, while the rest are arranged variously towards the margin, according to the genera 



and species. The seven plates which follow this cephalothoracic plate on the back of the animal 



represent so many abdominal* segments, but are connected with the corresponding sternal plates 



only by soft skin, with the exception of the seventh, which joins its sternal plate at the hinder part. 



The other six dorsal plates have only four distinct sternal plates to correspond with them, and 



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* Prof. Huxley speaks of them as thoracic. 



