1874.] 



ANATOMY OF THE PARROTS. 



595 



Division 2. The ambiens muscle wanting. 



Subfamily (5) Pyrrhurin^e. No further deviation. 

 Pyrrhura. 

 Lathamus. 

 Coracopsis. 

 Pyrrhulopsis. 



Subfamily (6) Platycercin.e. Furcula lost. 

 ( Platycercus, 

 < Psephotus. 

 [ Cyanorhamphus. 

 Psittacula. 



Subfamily (7) Chrysotin^e. 

 f Chrysotis. 

 \ Pionus. 

 Brotogerys. 



Oil-gland lost. 



In phyllogenetic language this arrangement would be expressed 

 thus : — The original stem, in which the carotids were normally dis- 

 posed, gave off a branch characterized by their abnormal arrangement. 

 The continuation of the main stem, as well as the branch, shortly 

 lost the ambiens muscle — the latter (and not the former), however, 

 being represented at the present day in its unmodified form by the 

 Arinse. Each of the two secondary branches persist as the Palseor- 

 nithinse and the Pyrrhurinse respectively, they both branching 

 dichotomously in an exactly similar manner, the former giving rise 

 to the Stringopinse and the specially modified Cacatua cristata and 

 C. sulphured, the other to the similarly modified Platycercinse and 

 Chrysotinse. 



A method of formulation will assist in making this more readily 

 intelligible. If the presence of two carotids, normally disposed, is 

 represented by the figure 2, the abnormal arrangement may be re- 

 presented by 2. Then, if the presence or absence of the varying 

 structures be represented by + or — , the following Table will 

 express the characteristics of the different subfamilies : — 



The Palaeornithinae will thus be represented by the formula 

 2, — , + , + ; the Arinee by 2, +, +, + ; and so on. Plate LXXI. will 

 represent these facts in a more self-evident manner. 



Through the kindness of Prof. Flower and also from the death of 



