PSITTAOI 257 



Chrysotis versicolor. Ghrysotis Bodin. 



„ erythrura. „ viridigenalis. 



„ leucocephala. „ Levaillanti. 



In all these species the first two rings of the bronchus 

 are closely fused together, and form a bowed piece of bone 

 forming with the last tracheal ring a semicircular outline ; the 

 space between the two is, of course, occupied by membrane. 

 In Chrysotis Levaillanti, for instance — and there is no great 

 difference in the other species — the double character of the 

 apparently single first bronchial semi-ring is only to be seen 

 at the two ends. In a number of other parrots the first 

 bronchial semi-ring is larger than that which follows, though 

 not fused with it ; this is the case with Trichoglossus, 

 Pyrrhulopsis, and Chalcopsitta ; the genera Eos, Polyteles, 

 Platycercus, and Tanygnathus have syringes which are con- 

 structed on the same plan. In Conurus there is a little 

 difference ; here the first two rings of the bronchus are equi- 

 sized ; this at any rate applies to the two species Conurus 

 aureus and Conurus cruentatus, which are the only two that 

 we have examined from this point of view. The genus Ara 

 (species Ara Leari, Ara militaris) agrees with Conurus. 

 Psittacus is like these genera ; but Pionus agrees more closely 

 with Chrysotis. 



~ It will be obvious that no hard and fast line can really 

 be drawn between the two groups of parrots ; if it were 

 thought desirable to draw such a line, it would be between 

 the genus Cacatua on the one hand and all the remaining 

 parrots on the other. Cacatua alone has a syrinx in which 

 the first bronchial semi-rings are incomplete, leaving a bare 

 tract laterally which is easily visible when the syrinx is 

 viewed from the side : but in this genus there is another 

 pecuUarity — the intrinsic muscle of the syrinx ends in a very 

 narrow point, which passes into a fine tendon of attachment ; 

 in Chrysotis, Eos, &c., the muscle is comparatively broad 

 down to its actual attachment. In this particular Micro- 

 glossa and Stringops agree with Cacatua, although they do 

 not show the incomplete rings that have been mentioned as 



