_—.* 
53 
in this species can only be discerned when the bird is living, 
and in its tendency to diurnal habits. But in the instance 
now recorded it exhibits other peculiarities of habit which 
afford a still more remarkable line of distinction. The point 
of Magilligan, forming the Derry side of the opening of 
Lough Foyle to the sea, is studded at its extremity with nu- 
merous sand hillocks, in which the rabbits burrow and the 
sheldrakes lay their eggs, as in other similar localities. But 
here a new occupant for the burrows of the rabbits appears in 
the otus brachyotos. These birds are regular in their au- 
tumnal appearance, and are seen to sit at the openings of the 
burrow-holes, and to run into them when disturbed. 
Captain Portlock having directed further attention to the 
fact, and pointed out the necessity of guarding against any 
source of fallacy, the truth of the first statement was fully 
established, more than one having been shot on emerging 
from the holes, and another actually caught in a trap at the 
mouth of a hole when endeavouring to make his escape. This 
interesting fact naturally recalls to recollection the stria cuni- 
cularicis of America, described by Say; and Captain Port- 
lock pointed out the great value of characteristic traits of 
_ habit in elucidating classification, and suggested the peculiar 
importance of those described in his paper, in affording a 
link of resemblance between the stria cunicularicis and the 
otus brachyotos, and thereby facilitating the determination 
of the true place, in natural classification, of the former, 
hitherto considered doubtful. 
The Secretary communicated the substance of a paper 
** On the Conic Sections,” by James Booth, Esq. 
The methods hitherto adopted in deducing the central 
and focal properties of the conic sections, from arbitrary 
definitions having appeared to the author defective in geo- 
metrical elegance, he has endeavoured in this paper to derive 
