L'l><; PTILOTA. 



the animal is not so dependent upon metamorphosis a* in 

 the subsequent perfectly metamorphotic division. Thus 

 there are many species In-longing to this section, which re- 

 main throughout their life in a state of imperfection ; of 

 which a common instance occurs in the Hydrometrida, or 

 water-measurers. These insects, which are to be observed 



Fig. 44. Apterous imfO-4i, Wiagcd Imago of Vclia rlvnloram. 



skimming along on the surface of the water, are generally 

 found destitute of the slightest rudiments of wings : they, 

 however, continue their kind, but occasionally certain indivi- 

 duals will be found in company with them with the uings 

 fully developed. Now it is impossible to regard the former 

 as pupa?, because they have no rudiments of wings ; neither 

 can we consider them as larva?, because they are as large as 

 the winged individuals, and are able to propagate. Accord- 

 ingly they have been generally regarded as distinct apterous 

 species; but a more extended investigation of these groups 

 of insects will prove the specific identity of these imperfectly 

 developed, but still perfect* (as regards their powers of pro- 

 Duration), individuals with the winged specimens. Thus. 

 there are many species, which, instead of being generally 

 wingless, are furnished \\itli short rudimental wings, and 

 which are nevertheless capable of reproduction ; hence, as 

 well as from the structure of the rudimeutal wings, it is 

 evident that they cannot be pupa*, and yet it occasionally 



* " The true criterion of animal as well as vegetable perfection is the 

 ability to continue the species." MACLK\ Y, llora Entomologies, p. 446. 





