234 FACULTIES OF BIRDS. 
the eagles be gathered together ;”* and in Job it is 
said, ‘‘ where the slain is, there is she.” Now itis 
well known that the eagle does not feed on carrion, 
and it has been proved, by experiment, that it will 
not touch it unless pressed by hunger. Yet Pro- 
fessor Paxton contends with St. Jerome that the 
eagle is certainly meant in the text, and quotes 
after Bochart, the Arabian historian Damir, who as- 
serts that the eagle can discover a carcass at the 
distance of four hundred parasangs, with this singu- 
larity that if he find part of it have been previously 
eaten by the osprey, he will not touch the leavings 
of his inferior. This circumstance, as it appears to 
us, makes rather against than for Dr. Paxton’s opin- 
ion, supposing the authority of Damir to be good. 
In consequence of this apparent discrepance be- 
tween facts and the text, St. Chrysostom proposed 
to read “vultures” for “eagles,” in the passages 
both in Matthew and Job. Aldrovand, we think, 
has given the only judicious solution of the diffi- 
culty by referring to a very common oriental spe- 
cies (Gypaétus barbatus, Storr), which was remark- 
ed by Aristotle to be similar in form to the eagle, 
but had more the habits of the vulture. 
Besides the nictitating membrane in the eye of 
birds already described, which is not altogether pe- 
culiar to them, there is another singular part of 
the organ whose use has not hitherto been clearly 
ascertained. It. is called by the French Academi- 
cians the purse (marsupium), and the comb (pecien 
plicatum). It arises in the back of the eye, and 
proceeding, apparently, through a slit in the retina, 
it passes obliquely into the vitreous humour, where 
it terminates, reaching in some species to the cap- 
sule of the lens. Numerous bloodvessels run in 
the folds of the membranes which compose it, and 
the black pigment by which it is covered suggests 
* Matt. xxiv., 28, and Luke xvii., 37, 
