1893.] THE AJS'ATOMT OF PARROTS. 509 



the bronchus are at first A-ery 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 riglit across the syrinx. In 

 Microgloi'sa aterrima the syrinx is in certain respects less abnormal ; 

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

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

 tract of membrane such as we have figured in Cacataa. 



Calt/ptorhifHchus bdiilsi 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. 



iStri)i//ops Imhroptilus (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 : — 



Chriisotis. Tanygaathus. 



Pyrrhnlopsls. Eos. 



Triclioglossus. Poly teles, 



Lorius. Platycercus. 



Pioniis. 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 bronchial semirings are straight. 



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

 genus we have seen the following species : — 



Chrysotis versicolor. 



eryfhrura. 



hucocepliala. 



hodln. 



viridiyenalis, 



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 tlie last tracheal ring a semicircular oulline ; 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 

 bronchia] semiring is only to be seen at the two ends. Jn a 

 number of other Parrots the first bronchial semiring is larger than 

 that which follows though not fust^d with it ; this is the case 

 with 2Vichoylossiis, Pi/rr/iHlojisis, and Cludcojtsllta ; the genera Kos 

 (figs. 1, 2), Polytelts, Platyccrais, and 'Panyr/tuUhns have syringes 

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



