HYDROPHiL. Q7 



common error, and ascertained the real structure 

 of the animal, which he has clearly and satis- 

 factorily explained. 



The larvae of the Hydrophils are supposed to 

 remain about two years before they change into 

 pupae or chrysalides. When the larva is arrived 

 at its full growth, it secretes itself in the bank of 

 the water it inhabits, and having formed a con- 

 venient cavity or cell, lies dormant for some time, 

 after which it divests itself of its skin, and appears 

 in the form of a chrysalis, in which state having 

 continued for some time longer, it again delivers 

 itself from its exuviae, and appears in its complete 

 or beetle form. When first disengaged from the 

 skin of the chrysalis, it is of a pale colour, and 

 very tender ; but in the space of a few hours the 

 elytra or wing-cases acquire a degree of strength 

 and colour, which gradually grows more and more 

 intense, till the animal, finding itself sufficiently 

 strong, comes forth from its retreat, and commits 

 itself in its new form to the waters. 



The male is distinguished from the female by 

 the structure of the fore-legs, which, as in the genus 

 Dytiscus, are famished, near the setting on of the 

 feet, with a sort of horny, concave flap or shield ; 

 the legs of the females being destitute of this part. 

 The structure of the hind-legs is finely calculated 

 for the animal's aquatic mode of life, being fur- 

 nished on the inside with a series of close-set 

 filaments, so as to give a sort of finny appearance 

 to the legs, and to enable the animal to swim with 

 the greatest ease and celerity. It may be added, 



v. vi. P. i. 7 



