LOSS OF COLOUR. 205 



another green, another copper, another purple, another red, 

 while another is as made of burnished gold. 



The larvae of these Beetles live within the stems of the 

 various water-plants, and on that accoimt the species have 

 derived their names from the plants on which they live. One 

 species, for example, takes its name from the bog-bean, or 

 yellow water-lily {Menyanthes nymphceoides), on which it is 

 found. Another is named Donacia typhce, from the common 

 bull-rush or reed-mace {Typha latifolia). Another has the 

 name of Donacia sagittartoD, from the arrow-head {Saglttaria 

 sagittifolia) ; and so forth. Altogether, exclusive of varieties, 

 of which there are a great number, nineteen British species of 

 this beautiful genus are known. In some places these Beetles 

 are so plentiful that seven species have been found on water- 

 plants within the limits of one small pond. 



The present species is shining-green above with a brassy 

 gloss, and below it is silvery-white, owing to the soft down 

 with which it is clothed. There is a bold groove on the front 

 of the head, and the elytra are both striated and ' crenated,' i.e. 

 covered with little marks formed like segments of circles. It 

 is not a very common species, being rather confined to certain 

 localities. 



The next insect on our list is that which is shown on Wood- 

 cut XXII. Fig. 2, and is known by the name of Criocens 

 merdigera. It belongs to another family, the Crioceridoe. In 

 this family, the outlines of the eyes are notched, and the antennae 

 are set in front, within the inner margin. The mandibles are 

 short and abrupt at the tip, and have several sharp teeth. The 

 genus Crioceris has the palpi slender, the joints of the antennae 

 short, and the elytra wide. The name Crioceris is formed from 

 two Grreek words, signifying ' ram-homed,' and is given to the 

 insects on account of the form of the antennae. 



Only three English species of this genus are known, of 

 which the insect which is shown on the illustration is by far 

 the most remarkable. Its colour is bright scarlet, but unfor- 

 tunately, as is the case with many brilliant insects, the colour 

 only exists during life, and fades rapidly after death. This 

 fading is generally caused by want of moisture, and in some 

 cases has been checked, if not altogether stopped, by opening 



