PSITTACI 263 



whose relations in this particular to other parrots are almost 

 those of Didunculus to other pigeons.' 



The most recent and elaborate essay upon the osteology 

 of the parrots is by Mivaet,^ who has described the entire 

 skeleton of Lorius and Psittacus ; some of his illustrations 

 are reproduced here. Fourteen is the prevalent number of 

 cervical vertebrcB (e.g. Lorius, Psittacus, Platycercus,Gaica), 

 Stringops, however, has fifteen. The atlas is notched {Ara 

 militaris) or perforated (Pyrrhulopsis) for the odontoid 

 process. Five (Ara, Psittacus) or six {Platycercus, Pyrrhu- 

 lopsis) ribs articulate with the sternum. The sternum has. 

 as a rule an entire posterior margin, which in Licmetis is- 

 entirely unnotched and unfenestrated. Most parrots have a. 

 pair of fenestras which in Deroptyus and Microglossa are 

 converted into notches. The sternum has a spina externa,, 

 slightly forked occasionally (e.g. Psittacus erithacus, Callo- 

 cephalon), hut no spina interna. The carina is deep — deeper 

 in Platycercus .{without fuBcula) than in Gaica (withfurcula), 

 the species being approximately of the same size. The 

 furcula is sometimes present and. sometimes rudimentary. 



It is present, and forms a complete U, in Nestor, Conurus,. 

 Caica, Licmetis, Microglossa, Ara, PalcBornis, &c. 



An intermediate condition is observable in Eos, where the- 

 furcula thins much towards its sternal end. A still further- 

 reduction is seen where the two clavicles are separate below 

 and only bound by cartilage. Finally there are those parrots, 

 with a quite rudimentary pair of clavicles, consisting only of 

 a small piece of bone at the coraco-scapular end. This is the- 

 case, for example, with Pyrrhulopsis and Platycercus. 



The following table shows the number of cervical verte- 

 bras and the position of the first and last haemophyses in a 

 number of parrots : — 



' For structure of tongue see Ciaocio, ' Nota preventiva sull' interna, 

 struttura della lingua dei Papagalli,' Eendic. Sess. Ace. 1st. Bologna, 1877-8, 

 p. 157. 



^ ' The skeleton of Lorius flavopalliatus compared with that of Psittacus 

 erithacus,' P. Z. S. 1895. There is no account of the bones of the limbs,, 



