COLEOPTERA. — HYDIlOPITILrD^. 125 



trable to the water, being coated with a gummy secretion, whilst the 

 interior is composed of fine silk of a delicate white colour. This 

 cocoon is also described and figured in the Mag. of Nat. Hist. No. 18. 

 In the posthumous memoirs of Lyonnet, this cocoon is stated to be 

 composed of fine twigs of confervte ; but it is evident, from the more 

 precise statements of M. Miger, that silk and a gummy secretion are 

 the materials of which it is composed, the insect making use of the 

 plants only as a support, or perhaps a mould, whilst forming the nest. 

 The larvae arc hatched in about six weeks, or, in warm weather, in 

 twelve or fifteen days, according to M. Miger, and in a few hours make 

 their escape from their common prison. They very quickly attain the 

 length of two thirds of an inch, although the eggs were not half that 

 length. They undergo three moultings ; after the first of which they 

 are an inch long, after the second an inch and a half, and three inches 

 after the third {fig. 8. il.). They are of a long and somewhat co- 

 nical form, of a more fleshy substance than those of the Dyticidae, 

 with shorter and more slender legs ; the body is terminated by two 

 short filiform appendages, which the insect employs in respiration. 

 The head is horny, and of a singular form ; its lower surface being 

 very convex, whilst the upper is flattened (whence Frisch fancied that 

 the under side of the body was the back) ; the mandibles, also, which 

 are robust, and armed with a tooth near the middle of the inner edge, 

 are also elevated ; in these respects resembling the structure of the 

 larva of Cicindelae. The maxillae are elongated, and compose the 

 basal joint of what, at first sight, appears to be a pair of 5-jointed 

 palpi but which are, in reality, slender maxilla;, with apair of 4-jointed 

 palpi placed at the tip {fig. 8. 12. antennae and trophi). From the 

 position of the head and jaws, the larva is enabled to seize upon its 

 food, which consists of small aquatic mollusca and other animals inha- 

 biting the water, by suddenly throwing back its head and stretching 

 its mandibles ; it is moreover stated by Lyonnet, that it bends its 

 head so far back that it is enabled to employ its back as a table to 

 support its food, which it procures by first breaking the shell. It is 

 compelled frequently to come to the surface to take in a supply of 

 fresh air. Immediately upon seizing its prey, or being taken by the 

 hand, it becomes flaccid, and emits a blackish foetid fluid from the 

 mouth, accompanied by a slight noise. It is full-grown in July, when 

 it creeps out of the water, and burrows into the adjacent bank, in 

 which it forms an oval cell, by the assistance of an organ situated at 



