344 PRACTICAL AND SCIENTIFIC ZOOLOGY. 
should be here used, to avoid all confusion in the mind 
of the student. 
(424.) By Class is implied the first divisions of a sub- 
kingdom. The vertebrated animals are first divided 
into classes, which Mr. MacLeay was the first to desig- 
nate and define by their true characters: this name, 
therefore, is appropriated to those divisions which re- 
spectively contain quadrupeds, birds, reptiles, amphibia, 
and fishes: these are the classes of the sub-kingdom Ver- 
tebrata. Those of the annulose animals, on the other 
hand, have never yet been correctly made out ; it will, 
nevertheless, be our object, hereafter, to prove that the 
Ptilota, or winged insects, the Aptera, or wingless insects, 
the Cirripeda, or barnacles, the Vermes, or worms, and 
the Annelides, or red-blooded sea-worms, are so many 
classes, or first divisions of the sub-kingdom Annulosa ; 
representing, of course, those of the vertebrated circle. 
The classes of the other sub-kingdoms have never yet 
been defined with precision, nor will it be necessary, in 
this place, to cite further instances of this description of 
groups. 
(425.) Orders come next in rank to classes. Looking 
to the class of quadrupeds, we find there are five natural 
orders, following each other, however, in a somewhat dif- 
ferent series to what has been stated elsewhere.* In 
birds, again, the same groups occur, and they have been 
correctly designated in the following natural series t: — 
1. Raptores, or birds of prey; 2. Iysessors#s, or perch- 
ers; 5. Rasorgss, or fowls; 4. GRALLATORES, or waders ; 
5. NavraTores, or swimmers. The first divisions, also, into 
which both the apterous and winged insects are naturally 
grouped, are strictly classes ; of which Linneus, indeed, 
seems to have had an intuitive perception ; his Cole- 
optera, Hemiptera, Neuroptera, &c., being truly groups 
of this value, notwithstanding the dismemberment they 
have received from some of the best modern entomo- 
logists. In like manner the Acephala, or bivalves, and 
the Gasteropoda, or univalves, among the molluscous 
* Linnean Transactions. + Ibid. 
