612 S YS TEMA TI C S YNOPSIS. — PSI TTA CI. 



other side forms a delicate tactile organ. It is used to some extent in prehension, objects being 

 handled between itself and the upper mandible, and the palatal surface of the hook of the bill 

 is furnished in most genera with a set of parallel ridges forming a sort of file or rasp. The 

 tongue is borne upon a well-developed hyoidean skeleton, among the parts of which the large 

 entoglossal or glossohyal is highly characteristic, being foraminiferous, or consisting of paired 

 halves connected at the end by cartilage ; the basihyal develops a pair of parahyal processes 

 besides the usual urohyal, and the cornua are composed of long hypobranchials bearing j(jinted 

 ceratobranchials. Ability to articulate human speech is one of the most notorious faculties of 

 certain Parrots. This seems to be due to the lingual peculiarities just noticed, in connection with 

 certain syringeal formations, for the syrinx is peculiarly constructed, in several different ways. 

 The bronchial half rings may be weak and separate cartilages, or several of them consolidated 

 into a bony box ; there are three pairs of intrinsic muscles, and the extrinsic are inserted some- 

 times into the pleural membrane, instead of the sternum. Finally it may be noted in this 

 connection that the bill is used in climbing, like a hand ; the upper mandible being much more 

 freely movable upon the skull than is usual among birds. This mobility is secured by the 

 articulation instead of suture of the maxillae, premaxillae, and nasals with the frontal, palatals, 

 and jugals. The mandibular symphysis is strong, short, and obtuse; the lower jaw is like a 

 thumb as opposed to the finger-like upper jaw, and the jaws as a prehensible organ may be 

 likened to the claw of a lobster. 



Other osteological characters are : Palate desmognathous ; nasals holorhinal ; nasal sep- 

 tum much ossified ; bony orbits of eyes frequently completed ring-like by union of lacrymals 

 with postorbital processes of the squamosal ; no basipterygoids. Cervical vertebrae as a 

 rule 14, rarely 13 or 15; atlas either notched or completely perforated by odontoid process of 

 axis. Sternal ribs 5 or 6 ; sternum entire behind, or there fenestrate, more rarely with one 

 pair of notches. Furculum variable; weak, or without symphysis, or so defective as to be re- 

 duced to its coracoid end, or wanting entirely. Tarsometatarsus short and thick, its lower end 

 modified to suit the position of 4th toe. There are 3 decided modifications of the carotids — 

 right and left present, both running deep in the vertebrarterial canal ; or both present and the 

 left superficial ; or only the left developed. In the digestive system: a well -developed oeso- 

 phageal crop and zonary proventriculus ; gall bladder usually wanting (present in Cncatua) ; 

 intestines extremely variable in length in different genera (at a maximum in Edectus). Oil- 

 gland absent from certain genera, present and tufted in others. Plumage aftershafted, in many 

 cases including powder-down feathers, either aggregated in a pair of lumbar patches, or scat- 

 tered indefinitely ; spinal pteryla forked. Leg-muscles singularly variable : ambiens present 

 and normal, present and incomplete, or absent, hence the order is indifferently homalogonatous 

 or anomalogonatous ; femorocaudal, semitendiuosus and its accessory, present; accessory 

 femorocaudal absent, hence the normal formula A X Y, as usual in Picarian birds. Plantar 

 tendons desmopelmous in an ordinary way, in spite of the zygodactylism. 



Thus, though the order is so definitely circumscribed that no one doubts of any bird 

 whether it be psittacine or not. Parrots differ remarkably among themselves in certaiu struc- 

 tural characters which in most birds have a high classificatory value. The systematic position 

 of Psittaci between Picarice and Accipitres is probably the best that can be assigned in any 

 linear arrangement. 



The eggs of Parrots are plural, white, and almost invariably laid in holes with little or no 

 nidification ; the young hatch naked and helpless, but acquire down before fledging. The 

 order is mainly developed in tropical regions of both hemispheres, but has some representa- 

 tives in both temperate zones, extending from lat. 42° N. to lat. 55° S. " Parrots abound in 

 all tropical countries, but, except in Australia and New Zealand, rarely extend into the tem- 

 perate zone. The Indian and Ethiopian regions are poor in parrots, while the Australian is 

 the richest, containing many genera and even whole families peculiar to it " (Newton). A 



