SPIDER-LIKE ANIMALS 



385 



apparatus, and of these special interest attaches to Anurida mari- 

 tima, remarkable for its habit of floating on the surface of rock- 

 pools along certain parts of the coast. As remarked elsewhere, 

 insects as a rule are very intolerant of salt water. 



CLASS 2. SPIDER-LIKE ANIMALS (ARACHNIDA) 



This class is constituted by Scorpions, Spiders, Mites, and 

 other allied forms, though the affinities of some of these is more 

 than doubtful. The majority of species live upon animal matter, 

 and many of them pursue living prey. Arachnids are popularly 

 confused with insects, from which, however, they differ in many 



COMB 



Fig. 234. Scorpion, seen from above (A) and below (B). i, Chelicerse; 2, pedipalps; 3-6, walking legs. 



important particulars. These differences, as well as the points 

 of agreement, will be best understood by briefly describing a 

 Scorpion as a type (fig. 234). Spiders are more familiar to us 

 in this country, but as they are much specialized it will be better 

 to take them later. In dealing with the Scorpion, comparison 

 may well be made with the account of a typical insect given 

 on pp. 343-350. 



The obviously segmented body is protected by a firm horny 

 coating, which is very thick and hard in some places, while in 

 others it is comparatively soft and flexible, so as to permit of a 

 certain amount of movement. The body is not divided, as in 



VOL. I. 



25 



