Internal Ear of Birds, 8S 
so far inferior to them. According to Scarpa, this part contains 
only a hollow cartilage, in which the nerves of the cochlea ter 
minate. I have always considered this description as imperfect, 
and have found my opinion confirmed by careful examination 
of the internal ear of different birds. In the cochlea of the 
Falco lagopus^ Corvus glandarius^ Ardea stellarisy Fringilla 
Canaria, and Loxia coccothraustes, I discovered, beneath a cuti- 
cular disc or cover, a double row of cuticular folia, on the walls 
of which the greater portion of the cochlear nerve is distributed, 
while only one branch of it is distributed to the hollow cartilage 
of Scarpa. On the contrary, the cochlea of the domestic fowl 
had none of these folia, but was simple in its structure. In the 
duck, the foliated arrangement was present, but not so decided- 
ly marked as in the birds already enumerated. Probably the 
same is the case in the goose, but of this I have not satisfied my- 
self by actual examination. But Scarpa appears to have exami- 
ned only the cochlea of this latter bird, and hence we can explain 
how the structure we have pointed out has escaped his attention. 
Those birds which are remarkable on account of their acute- 
ness of hearing, are those also in which the cochlea is provided 
with perfectly formed cochlear plates. By means of the great 
number of these plates, a wider space is afforded for the distri- 
bution of the cochlear nerve, and probably the space is propor- 
tionally greater in birds than in the lamina spiralis of the coch- 
lea in quadrupeds. 
It is my intention soon to publish a full account of the fact, 
because a detailed description, without drawings, would not be 
sufficiently intelligible. I may add, for the information of those 
who may wish, by actual investigation, to satisfy themselves of 
the accuracy of my statement, that, in order to see the cochlear 
plates or folia, and the distribution of the cochlear nerve, it is 
necessary to harden the ear in spirits of wine, before dissection. 
Art. X.-— O/i the Aurora Borealis and Polar Fogs. By 
Professor Hansteen *. 
I. It is well known that, with us, the Aurora Borealis pre- 
sents itself to our view in the following manner. In the NNW. 
• From the Norwegian Memoir inserted in the Christiania Journ. of Nat. Hist. 
F 
