MArcH 29, 1901.] 
writers who did not take this method we 
may be allowed to read between the lines. 
A leading ornithologist (Alfred Newton, if I 
am not mistaken), suggests that in the case 
of Linnzeus we be allowed to ask the author 
what type he would have chosen if the 
modern problem were to be presented to 
him. Asto this weshould not be often left 
in doubt. If we are in doubt however, 
there is a very simple rule followed widely 
by naturalists, notably by Bleeker, the most 
voluminous writer on fishes. This is the 
selection, as type, of the first species named 
under the genus by its author, when other 
indications fail. This rule gives fixity, the 
sole essential thing. It gives justice. It 
saves a profitless overhauling of bibliog- 
raphy, and it is a clear way out of confusion. 
It is the only possible clear way. 
I suggest for consideration the following 
provisional rules for the application of this 
method : 
1. The type of a genus is the species 
designated as such by its author. 
2. If no typsis designated by the author, 
either explicitly or by clear implication, 
then the first species referred to the genus 
or the species standing first on the page, 
shall be considered as its type. A generic 
name should have no standing, if resting 
on definition alone, nor until associated 
with some definite species. 
3. To this rule the following provisional 
exceptions may be made. ‘The type ofeach 
genus of Linneus as stated by him is ‘ the 
best known Huropean or officinal species’ it 
contains. In case of doubt in the appli- 
cation of this rule, the species standing first 
may have the benefit of the doubt. Unlike 
most subsequent authors, Linnzeus usually 
placed his type species near the middle in 
the list of species. Cuvier made it his 
‘ chef de file.’ 
4. In case of genera based on old spe- 
cific names (Belone, Achirus, Trachurus) the 
species thus furnishing the name, if actu- 
SCIENCE. 
501 
ally mentioned by the author of the genus) 
may be regarded as its type. 
5. Possibly, toavoid confusion, it may be 
well to retain old generic names, restricted 
by common consent to a species not the 
first mentioned by the author, provided 
that such restriction antedates any modern 
names for the samegenus. Thus it may be 
well to retain Centropomus for Oxylabraz, 
instead of Lucioperca, Cheilodipterus for 
Paramia, instead of Pomatomus, Pomacanthus, 
for Pomacanthodes, instead of Zanclus. But 
I doubt the wisdom of this exception, and I 
shall not be surprised to see future writers 
following Bleeker in the use of Oxylabrax 
and Paramia, leaving the generic names of 
Lacépéde and of all writers since Linneus, 
to the first species named by their author. 
Davip STARR JORDAN. 
NOTE ON THE NUMBER OF PARTICLES IN 
THE SATURATED PHOSPHORUS 
EMANATION.* 
In a series of experiments made by pass- 
ing air ionized to saturation by phosphorus 
through a slender tubular condenser (60 
em. long, radii of air space, .30 cm. and .16 
em.), I showed that the electrical current 
radially through the condenser for a given 
potential difference, and the volume per 
minute of the ionized air sent longitudinally 
through it, were rigorously proportional 
quantities. At the same time the color of 
the steam tube observed on passing the air 
from the condenser into it, was invariable 
no matter whether the condenser was 
charged or not, cwt. par. Hence only an 
insignificant part of the particles producing 
condensation takes part in the electric cur- 
rent even with radial fields of 2,100 volts 
per cm., the highest safely admissible. I 
have estimated that less than 5 per cent. of 
* Preceding experiments in SCIENCE, Feb. 9, 1900, 
the above note being a sequel. I there gave relative 
values for the absorption velocities, absolute values 
being given in the Am. Journ. of Science, March, 
1900. 
