494 SYSTEMATIC SYNOPSIS. — PSITTACTY. 
III. Order PSIT#ACI: Parrots. 
Treet permanently zygodactyle 
by reversion of the fourth toe, 
covered with rugose granular 
scales or plates; bill short, ex- 
tremely stout, strongly epigna- 
thous, and furnished with a (fre- 
quently feathered) cere, as in the 
birds of prey; wings and tail 
variable. The parrots, including 
the macaws, cockatoos, lories, 
etc., form one of the most strong- 
ly marked groups of birds, as 
easily recognizable by their pecu- 
liar external appearance as de- 
fined by technical points of strue- 
ture. They were formerly in- 
cluded in an ‘‘ order” Scansores 
on account of the paired toes, but 
this is a comparatively trivial cir- 
Fig. 346. — Carolina Parroquet, reduced. (From Tenney, after Wilson.) 
cuinstance ; they have no special 
affinity with other zygodactyle birds, and their peculiarities entitle them to rank with groups 
valled orders iu the present volume. They might not inaptly be styled frugivorous Raptores; 
and in some respects they exhibit a vague analogy to the quadrumana (monkeys) among 
mammals. The tongue is thick and fleshy, in some genera peculiarly brushy ; it is used to 
some extent in prehension, objects being handled between the tongue and upper mandible. 
The upper mandible is much more freely movable than is usual in birds, being articulated in- 
stead of suturally joined with the forehead ; and the bill is commonly used in climbing. The 
bony orbits of the eyes are frequently completed by union of the lachrymal bones with -postor- 
bital processes, and in some genera develop a bony bridge across the temporal fossa. The 
symphysis of the lower jaw is short and obtuse. The sternuin is entire or simply fenestrated 
posteriorly; the furculum is weak, sometimes defective, or wanting. The principal metatarsal 
bone is short and broad, and its lower extremity is modified to suit the position of the fourth 
toe. The lower larynx is peculiarly constructed, with three pairs of muscles; the ability to 
articulate human speech is one of the most notorious faculties of some parrots. The plumage 
shows aftershafts; the oil-gland is wanting in certain genera; when present, it is tufted. 
There are no ceca, and the gall-bladder is wanting. Though the family is so perfectly 
circumscribed that no one doubts of any bird whether it be psittacine or not, parrots differ re- 
markably among themselves in certain structural characters which have in most. birds a high 
classificatory value. Thus, there are three decided modifications of the earotid arteries — « 
which right and left may both be present, and both running deep in the vertebrarterial canal ; 
or both may be present, but the left superficial ; or only the left is developed (in Cacatua), as 
usual in birds. The ambiens muscle, again, may be present and normal, present and incom- 
plete, or wanting altogether. The femoro-eaudal muscle, semitendinosus, and accessory semi- 
tendinosus are present; the accessory femoro-caudal is absent. 
The division of the Psittaci into family groups has taxed the ingenuity of ornithologists ; 
for so variously interrelated are the numerous forms, that the grouping fluctuates with almost 
every character or set of characters selected for use in classification. But Garrod’s admirable 
anatomical investigations show that the Psittaci may be ranged in two series, according to the 
