50 
SPECTACLE FLYCATCHER. 
the eye. We have had an example of this curious 
structure in the Prionops plumatus figured in our 
first volume, and it is also observed in the genera 
Ceblepyris and Perspicilla. What particular object, 
however, is effected by this singular appendage, is 
entirely unknown. 
Although we have no personal knowledge of the 
fact that the two birds, mentioned in the above 
synonyms, belong to one and the same species, yet 
there are many and strong grounds for the belief. 
Their size and proportions are the same ; the simple 
length of a dried skin, when measured from the 
tip of the hill to the end of the tail, depends in a 
great measure in the contraction or distention of the 
neck in the process of preserving ; they both in- 
habit the same districts, and are always sent to 
England from Senegal in pairs as male and female. 
But the chief reason for our forming this belief, is the 
fact, that in all the other species of Platysteira with 
which we aTe acquainted, the sexes differ in the 
same way ; that is, the male has the throat white, 
and the female red. Le Yaillant has shown this in 
two species*, and we have a third similarly coloured ; 
so that this variation in the colour of the sexes, 
becomes, in fact, one of the generic characters. 
Nearly all these species, moreover, have a sort of 
collar in front of their neck. 
The presumed male has the upper plumage of 
a deep black glossed until bluish; the wings are 
* Le Molenar, Ois. d’Af. iv. pi. 160. — Le Priprit, lb. iv. 
pi. 161. 
