470 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
The elders assumed certain forms as highest and ranged their series 
from high to low; the sons commence their series with the most gen- 
eralized types and progress from the generalized to the more spe- 
cialized. 
PROSPECTS AND NEEDS. 
In numerous old systematic and descriptive works—but in many 
cases not very old—the skeleton and other anatomical details were 
noticed in connection with the species described, but not seldom some 
of those details, if rightly interpreted, would be in contravention of 
the classification adopted. In fact, the anatomy was to all intents 
and purposes treated as an offering of curious but useless information. 
Such conceptions, happily, are mainly—but not entirely—of the past, 
and we may live to welcome the day when every animal will be 
treated as whole. Systematic zoology will then be regarded as the 
expression of our knowledge of the entire structure and as an at- 
tempted equation of the results obtained by investigations of all 
kinds. In fact, systematic zoology is simply an attempt to estimate 
the relative importance of all structural details and to correlate them 
so that their relative values shall become most evident. It is the 
scientific outcome of all anatomical or morphological knowledge and 
the aim is to arrange the animal groups in such a manner as to show 
best their genetic relations and the successive steps of divergence 
from more or less generalized stocks. 
One consummation devoutly to be wished for is general acceptance 
of a standard for comparison and the use of terms with as nearly 
equal, values as the circumstances permit. There is a great differ- 
ence in the use of taxonomic names for the different classes of the 
animal kingdom. The difference is especially great between usage 
for the birds and that for the fishes. For the former class, genera, 
families and orders are based on characters of a very trivial kind. 
For example, the family of Turdidee, or thrushes, relieved of formal 
verbiage, has been distinguished from neighboring families solely be- 
cause the young have spots on the breast, but even this distinction is 
now known to fail in some instances. Extremely few, if any, of the 
families of oscine birds are based on characters of a kind which would 
be regarded as of family value in other classes of vertebrates. On the 
other hand, many of the families and genera of fishes are made by 
some excellent authorities to include types separated by striking 
peculiarities of the skeleton as well as the exterior. The mammals 
are a class whose treatment has been mostly intermediate between 
that for the birds and that for the fishes. Its divisions, inferior as 
well as comprehensive, have been founded on anatomical characters 
to a greater extent than for any other class. Its students are numer- 
