236 FIELD ZOOLOGY. 



segments, pro-, meso-, and meta-thorax ; in each of which 

 characteristics they resemble the insects. In general 

 appearance, they look very much like spiders, but because 

 of these insect-like segments, they are called jointed 

 spiders. The Solpugida of the western states are found 

 in sandy regions, and are tawny and light brown in color. 

 Their mandibles stand straight out in front of the head, 

 and only the pincers of the mandibles are directed down- 

 ward, which is the position of the mandibles in the true 

 spiders. 



The maxillary palpi are very long, and besides being 

 used as guides to food selection, are also used as sensory 

 organs to warn of danger, and as organs of locomotion. 

 The front legs are without claws and are provided with 

 sense hairs, that is, hairs capable of conveying sense 

 impressions. So far as observation may be depended 

 upon, these legs are often used as palpi. 



With relation to the fact that the maxillary palpi 

 and the front legs may be interchangeable in function, it 

 may be remarked that on the basis of specialization of 

 organs these arthropods must be of lower rank than are 

 the arthropods in which there is no such shifting of 

 function. Accurate bases for classifying living beings 

 rest upon two supports, structural specialization and 

 mode of reproduction; and on these two bases the 

 jointed spiders would be classed lower than the true 

 spiders. They are rare; they eat small insects, and have 

 never been known to poison by their bite. 



Scorpions and False Scorpions. 



The true scorpions have the thorax unsegmented, the 

 head fused with the thorax, and the abdomen differentiated 

 into two portions a pre-abdomen, broad and consisting 



