REVIEWS. 313 
ance that if the difference in climate, etc., between Kansas and 
Pennsylvania has differentiated S. neglecta from S. magna, greater 
yet parallel discrepancies in physical conditions have not in the 
course of time changed yellow to red, and made Trupialis out of 
Sturnella. Refusing to name one short offset, we must refuse to 
name another, if a longer one ; and must add Trupialis militaris 
to the synonyms of Sturnella magna. The instability of “ spe- 
cies ” (which are practically our units of zoological computation) 
once admitted — and it is admitted by leaders in all branches of 
natural history — it becomes a logical necessity to admit a corre- 
sponding instability of all groups based upon an aggregation of 
these units; and if we are not to name Sturnella neglecta, because 
it is only a little differentiation of S. magna, we cannot consist- 
ently name a king-crab because it is great differentiation of a 
trilobite. All differentiations are or were once, gradual and im- 
perceptible; all are of degree only, not of kind; to name, or not 
to name, is a matter of individual discretion. Mr. Allen’s plan, 
fully carried out, renders our nomenclature simply an index of our 
skill or luck in tracing links between species; and if our efforts 
could be commensurate with his enthusiasm, we could not con- 
sistently name anything. 
To our mind, this forcibly illustrates the inefficiency of the Lin- 
næan nomenclature as an adequate method of formulating our 
knowledge. It answered, when a thing was either square or else 
it was round—when species were held for fixed facts as separate 
creations ; but now that we know a thing may be neither square 
nor round, but something between, it is lamentably eA 
Not many years hence, we trust, naturalists will have discarde 
for some better method of notation; and then the wonder will k 
that we advanced so far with such a stumbling-block in the way. 
Who shall say how much the advance of chemistry, for instance, or 
of philosophic anatomy, has been facilitated, or indeed rendered 
possible, by the invention of expressive symbols and apt formulas? 
or how much of the acknowledged confusion in zoology and botany 
flows from our cramped method of expressing our views? If we 
must continue to use a tool so blunt and unhandy as the binomial 
nomenclature, all cannot be expected to use it with equal skill and 
effect. — ELLIOTT Coues. 
