NATATORES. 255 
other orders and their subdivisions, may be traced in the pre- 
sent one; and its connexion with them, at various points, 
satisfactorily established by the tendency of particular ge- 
nera and species. It is also through the connexion of this 
order with that of the Raptores (however improbable it may 
at first view appear), that the circle of the orders themselves 
is completed. This seems, however, to be effected by the in- 
tervention of a peculiar form in the family of the Pele- 
canide ; I allude to the genus T'achypetes of Vir1tuor (the 
type of which is the Pelecanus Aquilus of Linnzus), of 
which the species, both in form, flight, and predatory ha- 
bits, shew a marked and near approach to the true raptorial 
birds. As the affinities of each family will be more particu- 
larly alluded to under their respective heads, I pass without 
further preface to that of the Anatida, with which the order 
commences. 
Famity I.—ANATID~. 
Tue Family of Anatide, to which we are introduced by 
the connexion subsisting between certain of its members and 
others of the preceding orders, forms the first aberrant fa- 
mily of the Natatores, and is formed of the extensive Lin- 
nean genus Anas with that of Mergus. The first it has 
been found necessary, by subsequent systematists (from the 
difficult task of reconciling and adapting the Linnean gene- 
ric characters to the vast variety of species it contains), to 
separate, either by sectional division, as adopted by M. 
TremmMtnck, in his “ Manuel d’Ornithologie” (which division 
is in fact equivalent to the subfamilies of the present sys- 
tem), or by the institution of distinct genera, the plan of 
IvuicEr, as well as other naturalists of the present day, and 
in which they do but follow the older ornithologists who pre- 
ceded the learned Swede. In conjunction, however, with the 
genus Mergus, it appears clearly to admit of being separated 
