LEAVES FROM MY NOTE-BOOK. 137 



Tubifex buries its head in the mud, leaving its tail-end waving to 

 and fro in the water, and draws itself in or out of its burrow by 

 means of four rows of hooks projecting from its body. In order 

 that the Dicranota larva may successfully follow the worms into 

 the depths of their burrows, it is necessary that they should be 

 able to travel at tolerable speed through mud and gravel. Five 

 segments near the hinder end of the body are provided with 

 paired feet, each furnished at the top with three circlets of hooks. 

 Almost the whole surface of the body is covered by a dense 

 growth of minute pointed hairs, directed backwards. But the 

 strangest provision of all is that for the safety of the head, 

 which can be completely retracted into the body ! The mouth 

 parts of the head bear a pair of mandibles with long curved 

 teeth, and the top of the head is defended with a strong shield. 

 Towards the tail are three pairs of tapering prominences, the 

 hindmost pair being very long and forming the extremity of the 

 body. These appendages are supplied with relatively large air- 

 tubes ; moreover, Dicra?iota has also a pair of spiracles, each con- 

 nected with a large tracheal tube, which runs along the body to 

 the head, giving off many branches to the various organs. The 

 larva seems absolutely indifferent as to whether it breathes atmo- 

 spheric or dissolved air ; but after its tail has been exposed to the 

 air, a bubble can often be seen attached to each spiracle. 



The " leaf-eating Beetles " ( Chrysomelidce) include a number of 

 species, which pass their early stages upon submerged plants and 

 feed upon the roots. The White Water-lily {Nymphcea), Pota- 

 mogeton, the i\rrowhead, the Sedges, the Marsh Marigold, the 

 Bulrush, the Horsetail, and other moisture-loving plants, yield 

 shelter to the various species of Donacia and its close ally, 

 Hcemo?iia. The female of D. crassipes (often found abundantly 

 on Nymph(2a or Sparga?iium) bites small round or oval holes in 

 the leaves, and through these apparently passes the eggs to the 

 under side, where she arranges them round each hole. The larvae, 

 when hatched, descend to the bottom, and begin to feed on the 

 roots. They exhibit no obvious adaptation to an aquatic life, no 

 swimming organs, no gills, no peculiar shape, but only the dirty 

 white colour, the small hard head, and the three pairs of pointed 

 legs, found in an ordinary larva which buries itself in earth. Yet 



