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POPULAR SCIENCE REVIEW. 
He entered into certain minuter details connected witli these main facts of 
oceanic circulation. 
ZOOLOGY AND COMPARATIVE ANATOMY. 
Organs of Hearing in Insects. — At the last meeting of the American 
National Academy of Sciences, Professor A. M. Mayer exhibited experi- 
mental confirmation of the theorem of Fourier as applied by him in his pro- 
positions relating to the nature of a simple sound, and to the analysis by the 
ear of a composite sound into its elementary pendulum-vibrations ; and to 
show experiments elucidating the hypothesis of audition of Helmholtz. 
Placing a male mosquito under the microscope, and sounding various notes 
of tuning-forks in the range of a sound given by a female mosquito, the 
various fibres of the antennae of the male mosquito vibrated sympatheti- 
cally to these sounds. The longest fibres vibrated sympathetically to the 
grave notes, and the short fibres vibrated sympathetically to the higher 
notes. The fact that the nocturnal insects have highly organized antennae, 
while the diurnal ones have not, and also the fact that the anatomy of 
these parts of insects shows a highly developed nervous organization, lead 
to the highly probable inference that Prof. Mayer has here given facts which 
form the first sure basis of reasoning in reference to the nature of the auditory 
apparatus of insects. 
Identity of American Hydra with European Species. — At a late meeting of 
the Academy of Natural Sciences of Philadelphia, Prof. Leidy made some 
remarks on the native Hydra, and described the common green and brown 
species. He stated that they had been regarded as distinct species from the 
green and brown ones of Europe, but he could perceive no difference. He de- 
scribed the habits of some of our Rhizopoda in eating Diatomacece; they absorb 
the chlorophyl and reject the silicious shell. Amceba devours Arcella. 
Relation between Colouration of Birds and Distribution. — M. Alph. Milne- 
Edwards remarks, in the u Comptes Rendus,” that in certain ornithological 
families (swans and parrots, e.g. ) the tendency to melanism, or black plumage, 
only appears in the Southern Hemisphere, and more particularly in the 
region comprising New Zealand, Papua, Madagascar, and intermediate 
parts. 
New Fish from the Bermuda Islands. — In u Silliman’s American Journal’ 7 
for August, Mr. G. Brown Goode says as follows : — u In a collection of 
fishes, including some seventy species, made at the Bermudas in the spring 
of 1872, I find two forms apparently undescribed, descriptions of which are 
given below. As the marine life of the Bermuda group is essentially West 
Indian in its character, these species may be regarded as additions to the 
ichthyological fauna of the West Indies.” Diapterus Lefroyi, sp. nov., and 
Engraulis Cheer ostomus. 
A New Order of Hydrozoa has been discovered by Professor Allman, who 
has recently published a very short account of them. The animal, which 
was discovered in the South of France, is attached to a sponge, and per- 
meates the spongy tissue. Although a hydrozoan, it is not a hydroid, and 
•cannot be referred to any of the existing orders of the hydrozoa. The 
