58 £. Billings on the Genus Athyris. 
which A. twmida does not occur. In preparing his description 
of the genus he may, however, have had that species before him, 
and its imperforate beak may have had some influence 
§ 5. “ When the evidence as to the original type is not sted and indis- 
putable, then the person who first subdivides the genus may affix the 
original name to any portion of it at his discretion, and no later author 
has a oie to es that name - any other part of the original genus.’ 
vision) can make noc e. He may amend by striking out 
the errors, if any there be, but all that is true must remain. 
I think that on a careful study of all the circumstances, it will 
. perceived that Mr. Davidson’s first adjustment of this question 
the most wise, the best for the interests of science, and the 
perfect accordance with them in every particular; and, therefore, 
a ties be a 
n one respect, however, it has been modified. Athyris as 
first defined by hie included Merista of Prof. Suess. This was, 
no doubt, due to the fact that the characters of this last named 
thi nus were not then accurately known to the scientific public. 
is makes Lg difference. Merista has long since been sepa- 
with its e M. Herculea; leaving the other and most 
important group be Athyris with ‘A. tumida for the type. 
ith regard to Spirigera, I think it can also be retained not- 
withstanding the following rule :— 
§ “When two authors define and name the same genus, both making 
it exactly of the same extent, the es name should be cancelled in toto, 
and not retained in a modified se 
If the name Athyris had aa extremely objectionable, accor- 
nal to the 1th rule, ecple might nate: cancelled it alto- 
most in that aneee The rules cannot be stretched to de- 
stroy; but they may be: strongly bent in the other direction, to 
preserve. Ifa generit name should be appropriate foralarge 
number of the species of the group to which it was originally __ 
applied, and not very objectionable as to a few only, I doubt that 
it can be changed. Such was the case — 
bigny objeoted to it. More ane two-thirds of the species de- — 
signated by him are imperforat and he should have retained 
the name for these. Some turalists were, therefore, in favor 
