150 =Mr. W. S. MacLeay on the Anatomy of the 
tothe organs they denote, and are compatible moreover with what ought 
to be our grand object in anatomy, namely, legitimate generalization (and 
not fanciful comparisons with the human subject), I shall of course have 
pleasure in adopting them. In some few cases indeed our venerable 
countryman’s nomenclature may be preferred for purposes of concise de- 
scription to that of M. Audouin, although for the philosophical view of 
the subject M. Audouin’s terms can scarcely with safety be altered, and 
have moreover the universally acknowledged right of priority. Thus, if 
I may be permitted by such naturalists as most properly insist on the 
right of those who give the first name, I would in the description of spe- 
cies prefer the use of Mr. Kirby’s terms prosternum, mesosternum and 
metasternum ; although to give a proper understanding of the compara- 
tive anatomy of insects, I would for the same parts use M. Audouin’s 
otherwise less convenientterms sternum of the prothorax, sternum of the 
mesothorax, and sternum of the metathorax. The nature and object of 
the present paper, however, preclude me from saying more on the subject 
of the “‘ Introduction to Entomology” ; this work being evidently, by its 
laying so much stress on differences, rather suited to some artificial system 
than to the study of the natural one, which depends on generalization. I 
shall therefore commence the present review of the Theory of Compara- 
tive Anatomy in Insects by repeating that M. Audouin’s Researches have 
so far the right of priority, and above all of philosophical criticism, as to 
justify me in pursuing the path he has pointed out. J am not, however, 
disposed to be a servile follower, and where I differ from him I shall have 
no hesitation whatever in pointing out the reasons for my dissent. 
It will be recollected by the readers of the “* Hore Entomologice”’ that I 
was inclined in that work to adopt the theory that every annulose animal * 
has a tendency to be decapod, or more properly to have five pairs of tho- 
racic appendages answering to the five thoracic segments. I also assigned 
my reasons for believing that although the typical number of segments in 
the body of an annulose animal might be fifteen, yet that the most general 
number of segments in the body ought to be considered as thirteen, the 
number in caterpillars and other larve : and I ventured to hint that all 
winged insects, I might have said all Annulosa, may be resolved into this 
* This theory, however, is only partially correct. 
a 
