36 REVIEWS AND BOOK NOTICES. 
in this country, numbering over two hundred specimens, and 
comprising the entire suites of the Smithsonian Institution, 
Museum of Comparative Zoology, and Mr. Lawrence’s collection, 
and an examination of the types in the collections of the Boston 
Society of Natural History and the Academy of Natural Sciences 7 
of Philadelphia, together with numerous specimens from other 
sources. In this paper Dr. Coues has adopted the ‘‘ synthetic” 
method of investigation instead of the ‘‘ analytic” which, up to 
the present time, has been so generally followed, especially by 
American ornithologists. It is hence a paper of unusual interest 
as fairly initiating a ‘‘ new departure” in American ornithology. 
Dr. Coues here takes the ‘ arbitrary ” but apparently justifiable 
basis of predicating ‘*‘ species ’} upon specimens presenting any 
definite, constant, tangible characters whatsoever, that do not, so 
far as it appears, grade into the characters of other species ;” of a 
predicating ‘‘‘ varieties’ upon specimens presenting indefinite and 4 
inconstant yet tangible characters that are seen to grade into 
the characters of other specimens ;” of predicating ‘“‘ ‘synonymes’ a 
upon specimens presenting indefinite, inconstant, and intangible 
characters, due to individual peculiarities, or to age, sex, season 
or locality ; as well as upon specimens presenting no special char- 
acters at all.” His investigation of the genus has led him to the 
belief “ that there are only four forms (sic) of Myiarchus that do 
not intergrade, and that are differentiated from a common original 
stock to such degree, or in such manner, that we cannot account 
for their respective peculiarities according to highly probable laws 
. of geographical variation depending upon differences in food, 
climate, etc.” He finds that the specimens examined by him “ rep- 
~ resent nine species, two of which present each three tangible varie- 
ties.” These results are somewhat different from those reached by 
other investigators of the group, and in allusion thereto be 
observes: ‘though in the following pages I may appear to — 
have ‘ unnecessarily,’ if not unwarrantably, reduced the number of 
=~ species, yet I am persuaded that no unprejudiced ornithologist 
could have reached different conclusions upon study of the same | 
material. It may be well to remember that two hundred speci- 
E Bull. Mus. Comp. Zool.. IIL p. 197. July. 1872 
-~ {Compa Omp ? p ı July, 1€ 
