Recent Literature . 
IOI 
1S83.] 
except 3 referred to Mimocic/ila , 12 referred to Catkarus , and 16 included 
in Merula . Merida (type Turdus merula Linn.) differs from Turdus 
(type Turdus viscivorus Linn.) only in coloration, and chiefly through the 
sexes being in Merula unlike in color when adult. The name Merula 
is thus held to be untenable for any species of North American Thrush, 
nor are any ‘‘generic” names other than Turdus recognized for any of our 
species, even (excepting Planesticus ) in a subgeneric sense. 
In regard to subspecies, or geographical races, Mr. Seebohm is emi- 
nently sound in theory, but, as we shall have occasion to notice later, is 
strangely illogical in his manner of designating such forms. “It is also 
due to the student,” he observes, “that some explanation should be given 
of the way in which conspecies [for this word he acknowledges his indebt- 
edness to Professor Schlegel] , or forms between which the difference is only 
subspecific, are treated in this volume. In the previous volumes of the 
‘Catalogue of Birds’ subspecific forms are recognized. This is an im- 
mense stride upon the hard and tight system of previous English ornith- 
ologists who refuse to acknowledge the imperfectly segregated species 
which undoubtedly exist in nature, because forsooth their binomial system 
of nomenclature does not easily lend itself to their discrimination. The 
American system, clumsy as it is, has undoubtedly the advantage of being 
far in advance of the old mode. ... It is very important that no mistake 
should be made as to what constitutes a conspecies. Two forms may be 
very closely allied ; but if the difference between them, however small it 
may be, is constant, and is not attributable to age, sex, or season, the 
probabilities are that it is a specific difference. On the other hand, if the 
two forms are so closely allied that they interbreed and produce fertile off- 
spring, which again interbreed, we may draw two inferences- — first, that 
the difference between the two forms is only subspecific, and, second, that 
between the two extremes must be an infinite gradation of intermediate 
forms. If the two forms have different areas of geographical distribution 
(which is usually the case), the intermediate ones will be found where the 
two areas overlap. If, from any cause, the species should be exterminated 
in the overlapping areas, and the causes which produced the variations of 
the two forms still continue, the peculiarities of each become emphazised, 
until they become so far sepaiated, that should their areas of distribution 
again overlap they will nevertheless not interbreed, and the two species 
may be considered to be completely segregated. Under these circum- 
stances, I have preferred to retain the binomial nomenclature for each of 
the extreme forms, reserving the trinomial name for the intermediate ones, 
uniting the two specific names by a hyphen, and placing the name of the 
bird first which it most resembles” (pp. ix, x). 
In reference to the above, it may be said that the author’s position, as 
here stated, in respect to subspecific intergrading forms (or conspecific, as 
our author prefers to term them) is a pretty fair statement of the ground 
taken ten years since by nearly all our leading American ornithologists, 
and from which basis they have since worked. It is this view of the matter 
that has given rise to our system of trinomial nomenclature for subspecific 
