74 A COMPARISON OF SPECIES. 



which, by virtue of their form, are a link between the earwigs 



and the spiders. 



These are its generic characters : 



The body elongated, cylindrical, garnished with long seti- 

 form hairs, and composed of eight segments, 

 six of which are perfectly distinct, and two 

 (the two latter) #ery short, and scarcely per- 

 ceptible; four-jointed antennas, longer than the 

 head ; long, slender, cylindrical feet ; forked 

 tail, silky, and transversely wrinkled; seven 



FIG. I5.--ZVI0- eyes, laterally grouped at the base of each 



na glactahs; a, 



en a ia u rged? ize; * antenna ; body without scales. 



The Desoria glacialis, a species at present unique, is of a 

 velvety black, and about one-sixth of an inch in length. 



The Podura plumbea (or "Spring Tail"), 

 common enough in England, and found 

 under all kinds of stones, will give the 

 reader an idea of the flea of the glaciers. 



1 



"f-^Kf On comparing these two species, we 



remark, first, that the Podura plumbea 

 is somewhat longer and thicker in body 

 than the flea of the glaciers (see Fig. 



FIG. 16. Poduraplumbea; 



a, natural size; ^enlarged. ifi . ^ ^^ ^ . ^ enlarged); but it 



is more particularly by the length of its antennae that we 

 distinguish it. It owes its specific name of Plumbea to 

 the livid blue or leaden colour of the scales which cover 

 its body. These scales resemble those of butterflies ; only 

 they are much smaller, more finely situated, and very 



