400 Recent Literature. Aue 
seasonal changes, (4) sexual differences, and (5) changes depending 
upon age’ (pp. 53-79); and ‘ Geographical Distribution’ (pp. 80-130). 
‘Migration,’ ‘Variation, and ‘Geographical Distribution’ are discussed 
from the broadest standpoint and with admirable conservatism. Migra- 
tion proper, though occurring to only a limited extent, is well-marked in 
the Indian Archipelago, but through lack of competent resident observ- 
ers its details are to a large extent unknown. In referring to the local 
movements of certain species of Pigeons at particular seasons the foillow- 
ing may be of interest: ‘‘ For the sake of the general reader, who may be 
apt to suppose that narrow straits of the sea offer no barrier to the geo- 
graphical distribution of tropical species, it may be mentioned that, so far 
from this being the case, there is reason to believe that resident species 
never, or very exceptionally, cross the sea; were it otherwise the species 
would not be found with such restricted ranges as is actually the case.” 
Under the subheading ‘ Hereditary effects of shelter and exposure’ 
(pp- 73-79), an attempt is made to explain the origin of racket-tail-feathers 
and other similar modifications of the plumage, which are believed to be 
due to ‘‘ the inherited results of attrition.” 
‘ Wallace’s line’ is considered at length under ‘ Geographical Distri- 
bution,’ the views of previous authors cited respecting it, and the conclu- 
sion reached that, in our present state of knowledge of the question it is 
a ‘‘ waste of time to speculate on it with the help of an up-and-down 
system for the islands and continents, just as required.” The distribu- 
tion of the Celebesian birds is tabulated and the relationships of the avi- 
fauna of Celebes as a whole and of the several lesser groups of islands is 
considered at length. “The results of our study of the birds of Celebes,” 
say these authors, ‘as well as of those of the countries around, is that by 
its avifauna Celebes has far stronger connections with the Philippines 
than with any of the neighboring lands, and that the relation of its 
birds with the Oriental Region is more than twice as strong as with the 
Australian Region.” 
In regard to methods of nomenclature in the case of subspecies, the 
authors, while freely employing trinomials for such forms, are not fully 
satisfied that some better system may not be devised. They say: ‘‘ Per- 
haps in future — when the want becomes sufficiently pressing to necessi- 
tate such a step —a somewhat considerable change in the nomenclature 
of the present day may be effected as follows: species as at present defined 
will remain under their original binomials; subspecies under trinomials ; 
but the degree of relationship between the interconnecting forms to these 
subspecies will be displayed by the use of numbers — somewhat after the 
manner of chemical formule. Thus, in the case of Halzastur tndus — 
taking four degrees of relationship into consideration — the typical subspe- 
cies will be Halzastur indus typicus, that of New Guinea H. indus girren- 
era; that of Celebes, which may be supposed to have three times as 
strong a connection with pgvrrexera as with typicus, will be represented 
as H. indus, girrenera,; that of Java being just about midway in charac- 
