252 ELEMENTS OF ORNITHOLOGY, 
and sexual characters.” Sometimes when a “ class” contains 
very many or very different “ orders,” the latter may be arranged 
in sets, each of which is termed a subclass. Similarly when 
there ane many families in an order, such families may be 
grouped in suborders; and sometimes the suborders have to be 
further divided into sections so that the families which compose 
it may be arranged in different sets. 
When also there are many genera in a family, such family is 
divided into subfamilies to receive different groups of such 
genera ; and very many “ subfamilies’? are found in Ornitho- 
logy. 
As we said in our introductory Chapter’, all Birds taken 
together form one class of Vertebrate, or back-boned, Animals, 
and all Vertebrate animals taken together constitute a primary 
divison of the Animal Kingdom called the Subkingdom Verte- 
brata. The class of Birds—the class Aves—has been at different 
periods divided in various ways. Divisions—more physiological 
than morphological—were instituted by both Linnzeus and 
Cuvier, on the lines of those differences of habit, and to a 
certain extent, of structure, which were referred to when we 
spoke * of the Scratchers and Cooers and Climbers, and Waders 
and Swimmers, and birds of Raptorial habit. 
By Linneus, Birds were arranged’ in six orders :—1. Acc?- 
pitres (Birds of Prey). 2. Pice (Humming-birds, Hoopoes, 
Crows, Birds of Paradise, Toucans, Trogons, Parrots, Wood- 
peckers, Wrynecks, uccous! Banbets, Hornbills, Kingfishers, 
Flycatchers, Honey-eaters, and Todies). 3. Anseres (Aquatic 
Birds). 4. Gralle (Waders, Ostrich, &c.). 5. Galline (Gallina- 
ceous Birds). And 6. Passeres (all the smaller Birds). 
Cuvier also arranged Birds in six almost similar orders, as 
follows :—1. Accipitres (Birds of Prey). 2. Passerine (including, 
with Linneus’s Passeres, also the Crows, Birds of Paradise, 
Humming-birds, Hoopoes, Todies, and Hornbills). 3. Scansorie 
(the rest of Linneeus’s “ Picee”), 4, Gallinacee (Gallinaceous 
Birds). 5. Grallatorie (Waders, the Ostrich, &c.). 6. Palmi- 
pedes (Aquatic Birds). 
He also subdivided his Passerinz into sections according to 
the shape of the beak in the way previously stated *. 
These classifications were long ago felt to be unsatisfactory, 
' See ante, p. 1. 2 See ante, pp. 67 & 181. 
° In the ‘Systema Nature,’ 1766, tomus i. 
4 See ante, p. 1382. 
