BULLETIN 
OF THE 
NUTTALL ORNITHOLOGICAL CLUB. 
Vol. IV. JULY, 1879. No. 3. 
ON TITE USE OF TRINOMIALS IN ZOOLOGICAL NOMEN- 
CLATURE. 
BY ROBERT RIDGWAY. 
In order to elicit a general expression of opinion in regard to the 
use of trinomials in zoological nomenclature, I adopt this method 
of answering the inquiries of several correspondents who have 
addressed me on this subject. It must, sooner or later, become 
evident to the scientific naturalist, that a strictly binomial system, 
while answering in the case of really distinct species, is entirely 
inadequate for the designation of those which are in the incipient 
stage. The use of a third term, therefore, becomes a matter of 
necessity in the case of forms which are not completely differen- 
tiated, i. e. which are not yet isolated by the extinction of inter- 
mediate specimens. In what manner this third term shall be 
connected with the generic and specific names is a question upon 
which scarcely two authors agree ; and as it is obviously desirable 
that some generally acceptable form be adopted, at as early a date 
as possible, we hope the subject may meet with due consideration.* 
* In the “American Naturalist,” Vol. V, 1871^pp. 346-373, Dr. Coues 
very strongly urges the employment of trinomials, and presents the most ex- 
plicit reasons why they should be used ; his excellent article should, therefore, 
be carefully read in connection with the present subject. The first ornitholo- 
gist to adopt the trinomial system of nomenclature on an extensive scale, so 
far at least as this country is concerned, was Professor Baird, who used them 
freely in that standard work, “Birds of North America” (Yol. IX, Pacific 
R . R. Reports), published in 1858, and subsequently in his “Review of Amer- 
ican Birds” (1864-66). The purpose of the present article is, therefore, not 
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