54 Mr. F. O. P. Cambridge—A Revision 
the original generic group to that to which it belongs by 
implication. 
On no account must all the species be removed from the 
title originally given to them; one at least must be left in, 
which in that case becomes the type. 
Where a generic name has been preoccupied, the loss of 
the name does not lessen the value of the group selected, so 
that a type may be selected for that group and another 
name given to it. 
These are the main features of the process, and I here 
give an instance to show more clearly how it works out in 
practice. 
For instance, the name Bombastes is given to a group of 
three species A, B, and C, which are the only ones originally 
included under that name by the author of it. The question 
is, which species must we regard as the type ? 
There are two processes by which the type can be deter- 
mined, either (i) by definite selection or (ii) by elimination. 
And both processes may be utilized in a selection. Under 
the first process (a) the author himself may select A, B, or 
C as the type; or (4) ancther author may select A, B, or C 
as the type; and the species so selected must be regarded as 
the type and no other. No author, of course, not even the 
originator of the genus himself, can definitely select as the 
type a species already removed either definitely or by im- 
plication under another generic name. If he has done so, 
his selection becomes null and void, because he had no power 
or right to make such a selection. 
Under the second process, where no type has been defi- 
nitely selected, one or two, but not ad/, of these species may 
be removed and placed under another generic name by any 
other author, thus “ breaking up” the original genus and 
“limiting” the generic name to one, or two, species; the 
last species left in being the type. 
If B andC are removed, A is left in and must be regarded 
as the type; if A and C are removed, B remains as the type; 
if A and B are removed, C is left as the type. If A be 
removed alone, then B or C can become the type either by 
definite selection or by a further removal of one of them. If 
B or C be removed, then the same remark applies to A, C 
or A, B respectively. The species left in are sometimes 
termed the ‘ res¢dual species.” 
It will be evident that the settlement 1s comparatively 
easy when any definite selection of the type has been made 
soon after the founding of the genus; but the matter becomes 
much more complicated when the genus, perhaps involving 
