REVIEWS. 741 
dichotomous — in two ‘ parallel series,’ based upon one physi- 
ological character, — Bonaparte; (2) a trichotomous, founded — very 
general considerations, eii and after him Lilljeborg; (3) quinary, 
a modification se the second, by dividing two of the three rt into 
tion of birds as modified reptiles — and carried out with ai novos 
to one anatomical character, afforded by certain cranial bones, — Huzle 
Each of these systems is reviewed at some length, their pini fotiziéé 
succinctly presented, and many of their deflciencies pointed out. 
In his remarks upon the Bonapartean system, Dr. Coues dE to di 
comparison of the two groups of birds termed Altrices and Precoces to 
are important, constant structural differences, whereas in the other no 
such differences exist. ** If helplessness at birth compared with precoc- 
s Dr 
in the scale, then either the reverse is the case w with mammals, or else we 
must compare altricial Zncessores with Marsupials, and proecocial Natatores 
with the higher orders: a dilemma either horn of which is — 
wur divisions of the latter. Hence, doubtless, as Dr. Coues par- 
tially suggests, birds, in regard to the eee of the young at birth, 
should be ` i 
compare i the Placentali he preecocial birds 
would then be comparable with the sae a ‘Waele s, (as rbi- 
vores,) and the altricial iem with the altricial or higher Placentals. T 
vast difference in the modes of generation between birds m ls, 
subclasses of mammals. It is nevertheless Mes that in the two great 
groups of birds first recognized by Oken — he Altrices and Precoces — 
but afterwards so thoroughly elaborated by edictis that the syste 
as all will Mb appropriately bears his name, there is something a 
forcibly recalls the t wo subclasses of mammals. This division, in the 
present iras dn peg separates birds into two highly nat- 
ural, primary series, with, to a great extent, parallel or representative 
groups in each, ai o distinct that no removal of any of the groups 
of the one series to e other can be made without bringing illy-asso- 
