34 
NGL TORE 
[May 21, 1885 
my former hypothesis of a stridulating organ.” 
acquainted with such organs will be of his opinion. 
Another insect, Homothetus fossilis, was said to have a small 
basal vein, considered to be homologous with the arculus of the 
Odonata, and therefore to form a connecting link between 
Neuroptera and Pseudoneuroptera. A new synthetic family, 
Homothetidz, was proposed. But now a re-examination of this 
wing convinces the author ‘“‘that he had been mistaken about 
this arculus.” It does not exist at all. 
The third insect, Platephemera antigua, was determined by me 
as the apical half of the wing of a gigantic dragon-fly. As this 
is the only species claimed now by the author to belong to the 
Ephemeridz, he defends vigorously his determination by four 
objections :—(1) ‘‘In no dragon-fly, living or fossil, is there 
found beyond the nodus between the mediana and margin, more 
than a simple longitudinal vein, the marginal vein.” If the 
author will examine any Odonate wing from 6.7ow, he will find 
such a vein, which is the prolongation of the subcosta, bent on 
the nodus to the marginal vein, and running close to it. Near 
the nodus it is more widely separated in larger species. (2) 
“ The reconstruction of the wing, after the dimensions given by 
Dr. Hagen, would, on the most favourable showing, make a wing 
of ridiculously extravagant appearance.” But such forms occur 
in living species of Tramea, Rhyothemis, &c.” (3) ‘‘The 
narrowing of the second cubital space is a common feature in 
Ephemeridz (six genera after the Rev. Mr. Eaton’s plates are 
quoted) ; and, as this varies in different species of the same genus, 
it seems to bea very unimportant matter.” I had purposely stated 
suddenly narrowing, and this does not exist at all in Ephemeridz, 
Everybody 
namely of in the six quoted genera, and cannot therefore vary in 
’ the different species of the same genus. It exists in Odonata. 
(4) ‘‘ The sector subnodalis does not run unbroken to the tip, 
as in all dragon-flies I haye examined, but is lost in reticulation 
shortly before the margin.” This last-quoted character is a very 
common feature in dragon-flies (Tramea, Rhyothemis, &c.). 
Only very exceptionally this sector runs unbroken to the tip in 
the large sub-family of Aischnidx (cf De Selys’s ‘‘ Revue des 
Odonates d’Europe,” p. 122). 
As all objections have been proved ¢o be ¢ncorrect, and only based 
upon insufficient knowledge of the venation of Odonata and 
Ephemeride, Platephemera belongs by the simple evidence of 
facts to the Odonata. The new proposed family of Palephem- 
eridze dies unborn, and the conclusions made from Palephemera 
are without value. 
The fourth species, Gerephemera, gives much trouble to the 
author, and he is now inclined to bring it into the same group 
with the Protophasmida. As only a part about 4 mm. b oad 
can be said to exist in both figures (Brongniart and Scudder) 
which could be compared, and as this part contains only a few 
sectors running to the margin, the relationship of Protophasma 
to Gerephemera is not at all obvious. The reverse of Gere- 
phemera contains more than the author has seen. The basal 
part of a hind wing to the sector trigonali inferior, the 
basal part of a front wing with the same sector, and some veins 
belonging, probably, to another (front?) wing. The part figured 
and described by the author belongs, probably, to the other hind 
wing. No student of Odonata will be in doubt that Gerephemera 
belongs to this family, perhaps near Isophlebia. His statement 
‘that the superior origin of the branches of the sector medius is 
entirely inconsistent with an Odonate hypothesis, and is the 
most salient point in the wing,” is directly recognised as an error 
by looking at the figures in De Selys’s ‘‘ Monograph Caloptery- 
gines” (cf Cleis, Vestalis, Neurobasis, &c.). This statement is 
only surpassed by the emphatic repetition ‘‘that the marginal 
would then be an elevated, and the mediastinal a depressed, 
vein, which combination ts never the case.” This statement is 
just the contrary to what exists in all Odonata—unless it is 
preferred to examine the wings from beneath. 
There exists still no monograph of the Sialidze ; therefore it 
is impossible to make conclusions and form new families for the 
other three Devonian species. The opinion on the Devonian 
insects given by Rey. A. E. Eaton (NATURE, vol. xxiil. p. 507) 
is still very just: ‘‘ Palacontologists have adopted a ridiculous 
course with regard to some insect fossils. Whenever an obscure 
fragment of a well-reticulated insect-wing is found in a rock, a 
genus is straightway set up, and the fossil named as a new 
species. The species is then referred to the Ephemerid, and is 
immediately pronounced to be a synthetic type of insects at 
present distantly related to one another in organisation. This 
enunciation of synthetic types is often nothing less than a resort 
at random conjecture respecting the affinities of animals which 
the writer is at loss to classify. I thought that the Ephem- 
eridz had served quite long enough as an asylum for fossil 
cripples. I wished to intimate gently, that refuse of other 
groups of insects should be henceforth shot elsewhere.” 
Cambridge, Mass., March 12 H. A. HAGEN 
High-Level Stations 
In NATURE, vol. xxxii. p. 17, I find the abstract of an address 
by Mr. Omond, on ‘‘ Ben Nevis.” There are many points of 
interest, but I regret that one was not mentioned—vyiz. the 
exceedingly rapid decrease of temperature with elevation from 
Fort William to the Ben, anything nearly approaching, in middle 
latitudes, being only found on the Brocken, and all high-level 
stations of the Alps showing a much smaller decrease. At the 
Brocken, as well as at the Ben, the great difference from the 
Alps is not in summer, but in the colder months of the year. 
The reason seems to lie in the nearly constant winds, which 
bring air from below, which is cooled by ascension. The cases 
of great dryness of the air with descending currents in anti-~ 
cyclones in the colder months of the year, when isolated moun- 
tains are often much warmer than the valleys,! are comparatively 
rare in the North of Scotland, but frequent in the Alps, and 
certainly must and do have a great influence on the mean tem- 
perature. Where they are frequent, as in the Alps—especially 
the eastern—the mean amount of decrease of temperature with 
elevation must be slower. 
I think all meteorologists will concur with me that the greatest 
points of interest in the Ben Nevis station is the study of the 
meteorological phenomena near the centres of cyclones, as no 
high-level station in the world is s» favourably situated as this 
for this study. A. WOEIKOF 
St. Petersburg, May 1 (13) 
Rainbow Phenomena 
Your correspondent Mr. C. Croft (NATURE, No. 811, p. 30) 
has noticed phenomena which are perfectly familiar to students 
of physical optics. The internal bands of colour within the 
primary bow are the ‘‘ supernumerary” bows due to diffraction. 
‘They were described by Langwith in the PAzlosophical Trans- 
actions for 1722: a partial theory of them was given by Young in 
1804, and a complete theory by Sir G. Airy in 1836. The illu- 
mination of the sky in the regions within the primary and with- 
out the secondary bows, and also the relative darkness of the 
space between the two bows, Mr. Croft will find the desired 
explanation in any elementary treatise on optics ; Osmund Airy’s 
Geometrical Optics may be cited as giving a good account of 
these matters. The particular bow seen by Mr. Croft appears 
to have been of unusual brilliancy ; did he notice any of the 
radial streaks, which I described in 1878 as frequently accom- 
panying rainbows ? S:LvaNnus P, THOMPSON 
Finsbury Technical College, May 16 
Aurora 
Last night at about 10.30 to 10.35 p.m. there was a well- 
marked aurora visible from here. It did not last long, the 
bright bands fading rapidly into a general glow towards the 
north. The wind, which was easterly yesterday, has gone round 
to north-west to-day with tendency to rain and low temperature. 
J. P. O’Remiiy 
Royal College of Science for Ireland, Stephen’s 
Green, Dublin, May 14 
Red Hail 
Mr, W. H. Mircuet, of Newry, has sent me the accom- 
panying note, which he thinks may be of interest to the readers 
of NATURE. C, EVANS 
Downshire Hill, Hampstead, N.W., May 18 
On May 7, Mr. R. A. Mullan, solicitor, of Newry, was driy- 
ing in a gig near Castlewellan, co. Down, when he was over- 
taken by ashower of hail. To his surprise he observed that 
some of the hail-stones—perhaps one in a hundred—were of a 
t This is well explained in the ‘Handbuch der Climatologie” of 
T. Hann. See also my paper in the Zeztschr. 7 Meteorologie, 1883, 
pp. 211, 241. 
