382 PYCNONOTID”, 
with black ear-coverts to the pale eastern forms with almost 
white ear-coverts. At the same time, all along the joining line of 
Molpastes h. burmanicus, M. h. vigripileus and M. h. bengalensis 
on the West with JZ. h. chrysorrhoides on the East we have not 
only many intermediate birds, which might equally well be 
assigned to either form, but there are many birds, the majority in 
fact, which can quite definitely be credited to one or the other. 
Thus there are in the British Museum Collection specimens from 
the Shan States, Yunnan, Siam, Karenni, Tenasserim, etce., 
some of which are labelled chrysorrhoides, some nigripileus, some 
atricapillus and some klosst but of the birds so labelled there are 
many of which it is impossible to say to which race they belong. 
Davison, Armstrong and others obtained birds at the same place 
about the same date which they had no difficulty in calling 
chrysorrhoides or wgripileus, yet others again are referable to 
either. It appears to me that all along the Siam—Burmese 
boundaries there is a narrow region in which there is no stable 
form found and where, evidently, there are such conflicting 
conditions in the environment that Nature has not yet had time 
to evolve one definite form. It is, of course, true that in all lines 
of demarcation between geographical races intermediate forms 
are the rule but in this intervening territory intermediate 
individuals are less common than such as can be definitely assigned 
to one or the other of the races in the adjoining area. 
In view of the many individuals which are exactly half-way 
between chrysorrhoides and their next-door neighbours, I propose 
in this werk to treat all the forms as geographical races of 
hemorrhous. 
Molpastes chrysorrhoides klossi Robinson, Bull. B.O.C., xli, 
p- 12 (1921) does not seem to be maintainable; the Museum 
series varies In wing measurements between 87 and 104 mm., 
whilst the very large series of Chinese birds range from 90 to 
107 mm., one huge bird from Amoy having a wing of 111 mm. 
On the other hand, it is quite possible that the birds of West 
Siam may be separable as somewhat smaller and darker on an 
average. ‘The series in the British Museum from that country is 
insufficient to determine this point. 
Key to Species and Subspecies. 
A. Under tail-coverts red. 
a. The black of crown sharply de- 
tined and not extending to the 
hind-neck. 
a’. Ear-coverts black and not dis- 
tinguishable from the crown. 
a. Back dark brown, feathers [p. 383. 
narrowly edged with white. M. hemorrhous hemorrhous, 
6". Back paler brown, feathers 
broadly edged with white . M. h, pallidus, p. 385. 
b'. Ear-coverts brown, contrasting 
with black of crown. 
