1S93.] THE AKATOMT OP PAEEOTS. 509 



the bronchus are at first very small and do not extend across the 

 side of the bronchus ; they gradually increase in length, until at the 

 sixth or seventh they come to extend right across the syrinx. In 

 Microglo^sa aterrima the syrinx is in certain respects less abnormal ; 

 the rings are still feeble, but on a lateral view of the organ tliey 

 extend completely across, and there is on such a view no bare 

 tract of membrane such as we have figured in Cacatua. 



Calijptorhipiclms bitnhsi is intermediate between the two extremes ; 

 the first semiring only is incomplete, inasmuch as it does not 

 reach from one side of the syrinx to the other — or rather we 

 should say from the anterior to the posterior side. 



Strinrfops hahroptilus (fig. 3) has the same weak cartilaginous 

 bronchial semirings ; but on a lateral view of the syrinx they are 

 seen to extend right across. 



b. The second group contains, so far as we can say from first- 

 hand knowledge, the following genera : — 



Chrysotis. TanygnatJms. 



Pyrrhulopsls. Eos. 



Trichorjlossus. Poly teles. 



Lorius. Platycercus. 



Pionus. Poeocephalus. 

 Psittacus. 



These genera, of several of which we have examined more than 

 one species, are differentiated from those of the first division by the 

 fact that the bronchial semirings are as a rule ossified and are 

 frequently more or less fused together ; at the same time the first 

 ring is commonly concave upwards, whereas in the Parrots of the 

 first mentioned group the broucliial semirings are straight. 



The most extreme type is perhaps offered by Chrysotis ; of this 

 genus we have seen the following species : — 



Chrysotis versicolor, 



erythrura. 



leucocephala. 



hodin. 



vindigenalis. 



levaillanti. 



In all these species (Plate XL. fig. 7) 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 semiring is only to be seen at the two ends. In a 

 number of other Parrots the first bronchial semiring is larger than 

 that which follows though not fused with it; this is the case 

 with Trichoglossus, Pyrrhulojms, and Chalcopsitta ; the genera Eos 

 (figs. 1, 2), Polytelcs, Platycercus, and Tanyynathus have syringes 

 which are constructed on the same plan. In Conurus there is a 



