170 MR. W. A. FORBES ON THE GENUS LATHAMUS. [Feb. 18, 



tract is observable, the inclosed space being of about the same width 

 as either of the tracts inclosing it, no tendency to a dilatation of 

 the arms at their junction (though there is some in front) being 

 present, and the rows of feathers in front having a more or less 

 clear 3.1.3 arrangement. The lumbar feathering is always very 

 weak ; so that the boundaries of the dorso-lurabar fork are very 

 clearly defined. Lathamus, however, differs from the above-men- 

 tioned forms a little by its longer and not so widely divaricated 

 scapular fork, and by the greater breadth of its inferior tract on the 

 sternum, thereby causing a corresponding diminution in the breadth 

 of the carinal space. The general agreement, however, of the ptery- 

 losis in the two types will, I think, at once be evident from the 

 figure of Lathamus (PI. XVI. figs. 1, 2), and that of Platycercus 

 pennmitii (PI. XVI. figs. 3, 4), which I have represented next to it 

 for the sake of comparison. 



If now we turn to the TrichofflossincB^ (See Pi. XVI. figs. 5, 6), 

 in which so many naturalists have included Lathamus,vie shall find 

 important and well-marked differences in the two tracts mentioned 

 above, though the general character of the pterylosis remains the 

 same in alP. The outer pectoral tract is never so narrow and distinct 

 liere as it is in Lathamus and its allies ; it is usually almost triangular 

 in shape, and so tolerably broad, shorter, and not so divergent, the 

 interspace between it and the main tract being much narrower, and 

 frequently with a few scattered feathers in it uniting the two tracts 

 together. The inferior tract on the breast is always much broader, 

 and the carinal space narrower. 



Still better-marked characters between the two groups are to be 

 seen in the disposition of the dorso-lumbar fork. This in all the 

 TrichoglossincB is extremely weak in front, the tracts not getting at 

 all strongly feathered till some way (in T. concinnus i inch) from 

 the ends of the scapular fork. Each arm is much shorter (in all the 

 forms I count about eight rows of feathers to the junction), wider 

 and more diffusely feathered than in the Platycercina, and becomes 

 dilated and more strongly feathered towards its junction with its 

 fellow, which takes place further from the tail than in the other 

 group. The united tract is strongly feathered and rather broad 

 at first, but narrows rapidly again towards the tail. Figs. 5 and 6, 

 PI. XVf. represent the pterylosis of Trichoglossus concinnus (a 

 bird a little larger than the "Swift Parrakeet'''), and show the 

 differences between the two groups, which, if somewhat slight, are 

 nevertheless easily appreciable after a little study, and are as well 

 marked as any others I have as yet observed in the pterylosis of this 

 order. 



Several points in the external characters of Lathamus show that 



' Of these I have examined the pterylosis in Eos rubra, Trichoglossi orna- 

 fus, hmmatodes, swains&iii, covcinnus (two specimens), and jriisillus, and 

 CcyriljMlusfringillaceus. 



^ I have as yet been unable to confirm Nitzsclvs observation (Picrylogr. 

 Eng. edit. p. 100) that in Lorins c/arridus and L. domiccUa the interior tracts are 

 continuous over the lower surface of the neck. 



