HELOPHORUS GRANTJLARIS. 109 



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 crea- 

 tures who live in the earth or under 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. 



HELOPHORUS GRAXULARIS. 



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 Pentainerous 

 Coleoptera, but of the family of the Palpicornes, the an- 

 tennse 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 favorite and valuable object. 



The sculpture of the elytra of Beetles is most remarkable ; 

 the ridges strengthen, the furrows lighten, the dots give air 

 to the spiracles beneath. In the Helophorus alternate rows 

 of large and small dots answer both purposes, and usefulness 

 as well as beauty write the wisdom of God upon the wing- 

 case of this little creature. 



