ON THE GENUS PTILOPUS. 63 



ciosus shows only a small violet stripe ; but the colours of their underparts 

 are such as to enable one to distinguish them at a glance. The most similar 

 to one another are P. speciosus and P. hellus ; they have a white breast-shield, 

 the upper part of which is citron-yellow. Besides, the belly has a large 

 patch in P. hellus rosy red, in P. speciosus violet ; the abdomen and under 

 tail-coverts are yellow, P. rivolii is more like P. hellus, but has the white 

 breast-shield entirely without the yellow ; the belly has a rosy-red patch, like 

 P. hellus ; the abdomen and under tail-coverts are sometimes yellow, some- 

 times green variegated with yellow. Lastly, P. miquelii has neither yellow 

 on the white breast-shield nor a red patch on the belly, notwithstanding it 

 has the red on the head; abdomen and under tail-coverts yellow. But a 

 small feature of P. miquelii, not to be overlooked or neglected, is a stripe of 

 bluish- green feathers bordering the white breast-shield below — a character 

 which contributes remarkably to the beauty of the species. 



"Except P. miquelii, all have been figured: — P. rivolii several times, 

 among others by Mad. Knip, Pig. ii. pi. 57, and by Des Murs, Icon. Orn. 

 pi. 4 ; P. hellus by Dr. Sclater, P. Z. S. 1873, pi. 57 ; P. speciosus by 

 von Rosenberg, Reistochten, pi. xv. 



"The bird in the Plate accompanying Mr. Rowley's paper was drawn 

 after a specimen killed on the island of Jobi, near Ansus, by myself in April 

 1873, now belonging to the Dresden Museum. 



"To characterize the four species better than words do, they ought to 

 be figured together on one plate. How Nature likes to vary the same 

 character, would be apparent to all observers as it is striking to every one 

 who sees the four birds together in skins. One cannot leave off speculating 

 how these differences may have originated. As they nearly coincide with 

 insular isolation, one might be inclined to connect these two circumstances ; 

 but at present we are totally at a loss to say why the males have altered in 



