160 ARCANA ENTOMOLOGICA. 
sary to be elucidated, as the character of the Ametabola of Leach 
(insects undergoing no metamorphosis) adopted by Mr. Denny, 
depends upon its existence. My own opinion on the position of 
these insects, given in my Introduction to the modern classification 
of insects, is called into question. As however I consider the 
fundamental characteristic of the class Ptilota to consist in a 
distinct metamorphosis involving the development of wings, 1 cannot 
admit the Anoplura of Leach into that class ; and my answer there- 
fore to Mr. Denny’s. question as to the class to which I consider 
these parasitic insects to belong, will be found in the development 
of my views on the primary divisions of the annulose animals given 
in the fourth page of my Introduction, where I have adopted the 
order Ametabola of MacLeay (with the omission of his Vermes) 
because it leaves the Ptilota distinct, whilst Mr. Denny unites the 
Thysanura and Anoplura as a primary division, with the metamo- 
photic insects, under the general name of Insecta, which I maintain 
ought to be applied to the whole of the annulose animals with 
articulated feet. Mr. Denny justly eulogises Dr. Burmeister as 
the “first authority for this tribe of insects,” although he properly 
rejects his division of the Anoplura into Rhynchota and Mallophaga, 
the former (Pediculidee) being united with the rostrated Hemiptera 
of Linnzeus, whilst the latter are grouped with the mandibulated 
Hemiptera or the Orthoptera of recent authors. 
Mr. Denny has carefully investigated the writings of preceding 
authors ; a few of the figures published in the posthumous work 
of Lyonnet, appear however to have been overlooked: thus, 
Lyonnet’s plate 4, fig. 4, represents a species found upon the 
heron, which appears to be identical with Liotheum importunatum. 
As a work upon the indigenous species of these insects it is in- 
valuable, but for the higher ends of zoological science, this group of 
insects still requires illustration. With the exception of a figure 
of the female organs of generation of the human louse, copied from 
Swammerdam, we have no attempt to exhibit the internal structure 
of these insects; and the only figures which are given of the 
details of the mouth from a single species (Pediculus vestimenti) 
are copied (and not quite correctly) from Burmeister’s Genera 
Insectorum, a few figures are indeed added of the trophi in situ of 
two or three of the mandibulated species; but the interest attached 
to the distinction of haustellated and mandibulated trophi in a 
group whose general habits are so entirely identical, required a 
much more precise examination of their structures in this respect. 
