30 Caprimilgus europe us, or Fern Owl. 
sessing such a degree of sensibility as to enable these birds 
to detect their prey the instant it comes in contact with it, 
although placed beyond the reach of sight. 
Allow me to add, also, an explanation of that particular 
portion of the intestine of he woodcock called the appendix, 
and marked letter 6 in your Seventh Number (Vol. II. p. 146. 
fig. 33.), and also shown as appertaining to the same parts in 
the snipes, but not referred to; the nature and use of which, 
though probably well known to your correspondent H. V. D. 
and his medical friend, may not be -equally understood by 
many of your numerous readers. 
Some of the processes by which the human foetus, as well 
as that of the Mammalia in general, is formed, exhibit pecu- 
liarities similar to those employed in the bird, but in others 
there are essential differences. 
In the first named instances, one source supplies both nou- 
rishment and aeration: in the egg of a bird the embryo receives 
nourishment from one source, aeration from another. During 
the last fifteen days of incubation in the common fowl, the 
yelk, mixed with a small portion of albumen, gradually passes 
into the body of the chick by a canal, of which this appendix 
has formed a part. On the evenGatlh day, the whole of the 
remains of the yelk and its investing membrane will be found 
within the abdomen of the chick ; cad the membranous tube 
connecting the capsule of the yelk with the intestinal canal of 
the young bird, having perfor med its destined office, becomes 
obliterated and almost entirely absorbed, leaving only the 
appendix marked 6 as a rudiment pointing out the precise 
point of termination in the intestine. This canal is the ductus 
vitello intestinalis of authors, and its rudiment varies in size in 
different species: it is large in the woodcock, snipe, and 
curlew, but small generally in the rapacious, passerine, and 
gallinaceous birds. I am, Sir, &c. 
Se Tue 
Art. VII. On the Caprimilgus europe us, or Fern Owl. (fig. 5.) 
By BARTHOLOMEWw DILLoy, Esq. 
Sir, 
I am convinced there is no circumstance connected with 
the exposition of the history of any animal that you will con- 
sider unimportant; and, since the time of Mr. White of Sel- 
borne, there has not beet; that I am aware of, any new fact, 
except one, added to his history of the fern owl. His account, 
certainly an interesting one, is that which all of our subsequent 
