WHIP SCORPIONS AND THEIR ALLIES 3183 



when on the move always hold their large pincers well to the front, so as carefully 

 to feel the way. But different species show considerable variation in the carriage 

 of the body, some like Buthus, holding it high, while others shuffle along scarcely 

 lifting it off the ground. 



Again, many of the larger species, such as those belonging to Scorpio 

 and Opisthophthalmus, live in deep holes, which they excavate in the ground by 

 means of their large and powerful pincers. Others, like the little flat scorpions of 

 South Europe {Euscorpius) , hide away under stones and tree trunks, to which 

 they cling belly uppermost; while others, like Buthus, dig shallow pits in sand, 

 just deep enough to allow their eyes a clear vision of their surroundings, with 

 the back on a level with the surface of the soil, and here concealed from view they 

 lurk on the lookout for prey. Sound-producing organs have been found in the 

 large, black rock scorpions of India and Africa; the organ, which Ifes between the 

 basal segment of the pincers and that of the first pair of legs, consists of a set of 

 tubercles and of a cluster of curved hair-tipped spines. When the scorpions are ex- 

 cited they wave their pincers up and down, and by thus scraping the spinules 

 against the tubercles emit a rustling sound, which has been compared to that pro- 

 duced by rubbing a stiff toothbrush with one's finger nails. This organ is equally 

 well developed in members of both sexes, and probably serves as a warning to 

 enemies to keep their distance. An analogous organ is found in the South- African 

 Opisthophthalmus, but in this case it consists of leaf-like hairs placed on the inner 

 surface of the mandibles. 



THE WHIP SCORPIONS AND THEIR ALLIES Order PEDIPALPI 



The members of the second order of the Arachnida resemble the scorpions in 

 having the abdomen composed of twelve segments, and the second pair of append- 

 ages transformed into huge seizing organs, but differ from them in a number of im- 

 portant characteristics. The legs of the first pair, for instance, are not used for 

 locomotion, but only as organs of touch, and have their last segment devoid of claws 

 and divided into a series of secondary segments. Moreover, in the rest of the legs 

 the feet are three jointed. The most marked distinctions are, however, found in 

 the abdomen. In the first place, this region is sharply marked off from the cepha- 

 lothorax by a deep constriction forming a narrow waist. There is no trace of 

 combs, and the first sternal plate is of large size, and entirely covers the ventral 

 region of the first and second segments; so that, although there are twelve dorsal 

 plates on this region of the body, there are only eleven sternal plates. The 

 breathing organs are of the same nature as those of the scorpions, namely, lung- 

 books; but instead of forming four pairs, situated upon the third, fourth, fifth, and 

 sixth sterna, there are only two pairs, of which the apertures are placed behind the 

 sterna of the second and third segments. The order is divided into a tailed group 

 (Uropygi), and a tailless group (Amblypygi). In the former the body is elongate, 

 both cephalothorax and abdomen being much longer than wide; and to the last 

 segment of the abdomen there is attached a movable tail corresponding to the 



