THYSANURIFORM TYPE OF LARV.E. 63 



being pointed : sometimes these points are so long as to 

 resemble horns ; in other examples they are very short, 

 and hardly conspicuous; while in some few, although 

 the hinder part of the head is pointed,, it is not divided. 

 The extremity of the body gives us another pecu- 

 liarity : this part, also, terminates in two pointed pro- 

 cesses., which, according to their length in different 

 examples, either assume the appearance of tails, or of 

 two little short spines. We have no very striking in- 

 stances of these horned caterpillars among those of the 

 European butterflies ; but if the student meet with the 

 larvae of any of the brown meadow butterflies, forming 

 the modern genus Hipparchia, he will have a very good 

 idea of the general character of thysanuriforin larvae, 

 the great developement of which is seen only in the 

 large butterflies of Tropical America. A few words 

 may be necessary in explanation of the names given to 

 these caterpillars. They have been called Thysanuri- 

 form, under a belief (and we think the supposition is 

 correct) that they represent the Lepisma or Thysanura 

 of Dr. Leach ; while, by terming them also Rasorial, 

 we point out at once their unquestionable analogy to 

 the rasorial birds. 



(60.) Let us now compare these types of lepido- 

 pterous larvae with the five great groups of birds and 

 quadrupeds : the test of their accuracy will consist, of 

 course, on the analogy by which each should mutually 

 represent the other. We commence, then, with the 

 iuliform type. The butterflies which proceed from 

 caterpillars bearing this form, are well known to be the 

 most perfect of the whole tribe. This is manifested by 

 their possessing six perfect feet adapted for walking. 

 Linnaeus was well aware that the swallow- tailed butter- 

 flies were the princes of the diurnal Lepidoptera, for he 

 places them at the head as the NoUles, and names the 

 species after the heroes of Greece and Troy. They are, 

 in short, the most perfect of all butterflies, whether we 

 regard their general structure, or the unrivalled beauty 

 of their form and colouring. Now, this perfection, in 



