384 



AEACHNIDA. 



her tent in search of food : some of the superposed sheets are fastened 

 together at their edges ; others are simply laid upon each other ; and 

 as the parent herself alone possesses the secret which enables her to 



Fig. 194 b . 



1. Female of Hydrachne globulus, represented of the natural size just previous to ovipo- 

 sit Ion. 2. The same magnified, and seen from below, showing the mouth or beak furnished 

 with two palpi, and the eight legs appended to four separate pairs of coxae ; between the hinder 

 pair may be seen the heart-shaped genital scale, and a little posterior to this a round orifice, 

 which is the anus. 3. Newly-hatched larva of Hydrachne globulvs. 4. Hinder part of an 

 aquatic insect (Nepa cinerea), to which numerous nymphae of Hydrachne indifferent stages of 

 growth are attached. 5. One of these nymphs magnified, exhibiting the head-like sucker pro- 

 vided with a pair of palpi, immediately behind which are seen two of the epidermic cases of 

 two of the old legs of the larva (the four others have fallen off), and posterior to these, five 

 pairs of little sprouts, which are the rudiments of antennae and legs : the median circle indi- 

 cates the position of the genital organs. 6. Represents the same nymph in its last stage of 

 development, seen in profile : the integuments are supposed to be transparent, so as to show 

 the young Hydrachne within, ready to escape. 7. Ventral surface of young Hydrachne, showing 

 the arrangement of the coxae. 8. Secondary nymph making the transition from the second to 

 the third phasis of the creature's existence : the perfect animal, ready for its escape, is repre- 

 sented encased in the integuments of the preceding, the epidermic sheaths of the limbs still 

 remaining adherent to the exuvium. 



raise those layers hy which entrance is to be obtained, no other animal 

 can find its way into her impenetrable abode. 



(980 a .) The development and mode of exuviation of some of the 

 Acaridans offer several very curious and interesting phenomena. The 



