VOL. XVII.J PHILOSOPHICAL TRANSACTIONS. 331 



Anatomical Observations on the Heads of Fowls. By the late /lllen Moulen, 



M. D. S. R. S. N° 199, p. 711. 



In the heads of all the fowls that I had an opportunity to examine, I con- 

 stantly found only one aqueduct, or passage from the ears to the palate, whereas 

 in men, quadrupeds, and some amphibious fish, there are always two, one on 

 each side below the entrance of the nostrils into the palate, and opening to- 

 wards the nostrils for the more convenient reception of air, as is supposed. 

 This passage in fowls is exactly in the middle of the palate, below the entrance 

 of the nostrils into it ; it is a membranous tube, capable of admitting a raven's, 

 if not a goose quill in larger fowl, such as turkeys, geese, &c. and reaches 

 backward as far as the communication from ear to ear ; and hence it comes to 

 serve both ; whereas there is a necessity of two in those animals, whose ears do 

 not communicate. 



I have constantly found a hollow space between the two tables between the 

 OS cuneiform reaching from ear to ear, and as far forward as the aforesaid common 

 aqueduct, or rather ductus aereus, its mechanism seeming more to favour this 

 than the foriper use. This cavity in all fowl reaches above the labyrinthus on 

 each side, so that whatever impulse is made on the tympanum on the one side, 

 may not only be very readily communicated, by means of the internal air, to 

 the labyrinth of the same, but also to that of the opposite side. Hence pro- 

 bably proceeds the quickness of hearing and vigilancy of fowl, notwithstanding 

 the want of a cochlea ; the defect of which seems to be by this structure more 

 than supplied, no other creatures that we know of having any thing of it. It 

 is not improbable that the opposite ear to a sound is altogether as much affected 

 by it as that next it, if not more. There are several laminulaa and pillars of 

 hard bone, between the two tables in these cavities, designed as may be sup^ 

 posed, partly for their maintenance at a convenient distance, and partly for 

 isreaking the air, so as to prevent echoes and confused representations of 

 objects, as it has been ingeniously observed by Sir John Hoskins, that pillai^s in 

 churches very much prevented echoes. 



In the heads of woodcocks, besides the passages now described, I found one 

 on each side the bone, which makes the orbit of the eye, proceeding from the 

 ear, and reaching forward towards the setting on of the beak, near which 

 they joined in one, and turned under the skull in a small passage, leading to 

 the cavity by which the ears communicate, and which is above described, into 

 which it enters. These passages are also in the heads of snipes ; and besides, 

 one over the sinus longitudinalis, and another over the sinus lateralis of the 

 brain. 



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