126 



NATURAL HISTORY OF ARTPIROPODS. 



climates, produce very severe wounds which are attended with serious constitutional 

 derangement. Jousset, who has studied this subject, concludes that the poison o'f 

 the scorpion acts directly on the red corpuscles of the blood and on them alone. The 

 poison causes them to unite together in masses too large for entrance to the capillary 

 system, and thus the circulation is obstructed. The best remedy is ammonia applied 

 externally, and also administered in small doses internally. 



In the older schemes of classification the number of ocelli was used to divide the 

 group into families, but in the system now in vogue the shape of the sternum is em- 

 ployed, together with other characters. The family ANDROCTONID.E has this region 

 sub-triangular, in the TELEGONIDJE it is very short, while in the VEJOVID^E and PAK- 

 DINID^E it is sub-pentangular. These four families contain thirty-one genera, repre- 

 sented by numerous species in the warmer parts of the globe. Nearly twenty species 

 are known from North America. While most of the species are comparatively small 

 the Scorpio afer of the East Indies reaches a length of nearly six inches. The species 

 figured are all American. 



The scorpions are among the most ancient of the arthropods, forms closely allied to 

 those living at the present time being found in the rocks of the carboniferous age of 

 both Europe and America. 



J. S. KINGSLEY. 



FIG. 184. Nest of spider (Dolomedes). 



