104 Objects for the Microscope. 



elytron when in repose, the costal nerve ends abruptly, as 

 we see, at about half the length of the wing, and turning 

 backward into the post-costal nervure, forms a kind of 

 hook, strengthens the base, and allows of the easy folding 

 up of the tip of the wing. 



There is a particular provision made for the regulation 

 of the specific weight of the beetle's wing by means of a 

 long pocket just under the costal and mediastinal nervures, 

 called the Phialum, into which a liquid is introduced at the 

 will of the insect, which augments its powers of resistance 

 in flight. 



The veins, or nervures, are so placed throughout this 

 wing as to strengthen and stretch every part : at the same 

 time to admit of its being closely and easily folded under 

 the protecting elytron ; a most necessary arrangement for 

 creatures who live in the earth or tinder stones, or in the 

 water, where the delicate texture of the wing would be in 

 constant danger of destruction. 



Having thus examined one specimen of the Beetle tribe, 

 we shall be able with increased interest to look at another, 

 one of the small Water-beetles. 



HELOPHOKUS GRANULARIS. 



This is an abundant little creature in our ponds and 

 ditches, feeding on decayed or vegetable matter, and, being 

 easily procured, is selected as an example of a Pentamerous 

 Coleoptera, but of the family of the Palpicornes, the 

 antennse being very different from those of the Telephorus. 

 These are clubbed, composed of nine joints, and carried 

 backwards. 



It is a bad swimmer, and the legs are scarcely, if at all, 

 feathered ; the striped pro-thorax and the beautifully 

 dotted elytra make it a favourite and valuable object. 



The sculpture of the elytra of Beetles is most remark- 

 able ; the ridges strengthen, the furrows lighten, the dots 

 give air to the spiracles beneath. In the Helophorus 

 alternate row r s of large and small dots answer both pur- 

 poses, and usefulness as well as beauty write the wisdom of 

 God upon the wing-case of this little creature. 



