ody to retain it rigidly in their care and not to send such material 
away from their fireproof and well munitioned rooms, exposing it 
to the risks of breakage and fire. This rule should not, however, 
be too rigidly enforced to the detriment of science. There arise now 
and then cases in which in the interest of science it is desirable 
that types should be sent from one museum to another for purposes 
of comparison and investigation, or to eminent specialists who 
require this material in the preparation of monographic papers. 
Each case of this sort, however, should be made the subject of 
definite inquiry, and the utmost precaution should be taken to 
insure against the loss of specimens. As a rule I think that cotypes 
should be selected for transmission in such cases, when they exist, 
and that types themselves should not be exposed to the dangers 
of travel and of fire on sea and land. 
In this connection it remains for me to say that whenever great 
museums such as I have indicated entrust their collections to 
scientific specialists for study and determination, it should be the 
invariable rule that the types of the species named and described 
by such specialists should be returned to the museum from which 
they came. The claim was made a few years ago by one or two 
persons, who were, Lam sorry to say, entomologists, that it is the 
unwritten but universal law that an author is always entitled to 
reserve for his own collections the types of species which he may 
name. I took occasion at the time to memorialize the leading scien- 
tists of the day as to the existence of such «unwritten and invariable 
law », and discovered, as I knew I would, that there existed so far 
as I could ascertain only three or four persons in the world who 
claimed that such a law obtains. The law existed only in the 
disordered imaginations of my correspondents, and the mere sug- 
gestion of its existence was ridiculed by the most eminent systema- 
tists of the world. 
For my own part, I desire to say that I make it a rule to require 
of all specialists the return of the types to the Carnegie Museum, 
but am always ready, should there be sufficient material to justify 
me in so doing, to accord to students for their own private use 
such duplicate material as I may have at my command, and with 
