Genus— PE 0 S E I S U R A. 
Mathews, Bull. Brit. Orn. Club, Vol. XLI., p. 35, 
Nov. 30, 1920. Type (by original designation) Arses lorealis De Vis. 
Aeter continued consideration I decided to introduce the above new name 
to attract attention to a matter which would otherwise be overlooked, as it has 
been up to the present. This species was described as Arses and is separable 
from Ophryzone by its normal feet. Compared with Arses the birds are smaller, 
the bill broader and less hooked, the wing is rounded, the fourth and fifth 
primaries longest, the third and sixth subequal and a little less, the second much 
shorter and twice the length of the first. The tail is long and square. The feet 
have the toes and claws normal, the tarsus obsoletely scutellate in front. The 
male is black and white, the female nearly similar. 
This suggests that Seisura is an Australian derivative of the ancestor of 
this form, and its large size and distinct appearance are due to its isolation. 
It is remarkable that the northern form of Seisura more nearly approaches this 
bird in size, though it has a much longer bill ; in the south where a much larger 
bird has evolved, in some cases the bill has not been proportionately elongated. 
The rictal bristles are well developed in the present species, while they are obscure 
in Seisura , and the bare eye rim is absent in the latter. The relationships will 
be better realised through study of the nestlings and plumage changes than by 
osteological study, though the latter should be undertaken in conjunction with 
a series of Monarcha , Piezorhynchus birds. It may be noted here that a species 
of Monarcha has an eye rim while retaining the typical Monarcha coloration, 
and that Mr. Campbell has recorded that the eggs of these species recall those 
of Monarcha. 
VOL. IX. 
73 
