so Caprimulgtis europce\is, 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 the woodcock called the appendix, 

 and marked letter b 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- 

 harities 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 twentieth day, the whole of the 

 remains of the yelk and its investing membrane will be found 

 within the abdomen of the chick ; and the membranous tube 

 connecting the capsule of the yelk with the intestinal canal of 

 the young bird, having performed 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. 



S. T. P. 



Art. VII. On the Caprimulgus europm^us^ or Fern Owl, (fig. 5.) 

 By Bartholomew Dillon, 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 been, 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 



