Ivi 



INTRODUCTION. 



pressed corselet, and the large, sessile eyes. On its 

 . , first escape from the egg (fig./"), the 



feet are in two pairs, dichotomously 

 branched and destitute of hairs ; 

 the tail comparatively short, the 

 terminal flap somewhat lozenge- 

 shaped, and armed with long, slen- 

 der, bristle-like appendages. From 

 the anterior part of the carapace hang 



two long, slender filaments which turn under the thorax. 



In a few hours the first exuviation takes place, and the 



animal appears under a different aspect (fig. g}. Tl 



Fig. g. 



branchial members are converted into two pairs of simp] 

 Fig. Ji. three -jointed tufted feet. The 



hairy tufts are appended only to 

 the last joint. The terminal seg- 

 ment of the six-jointed tail (fig. h) 

 is expanded into a large quadran- 

 gular surface, the inferior mar- 

 gin of which is fringed with six 

 pairs of long slender filaments. 



