Entotympanic Muscle in the Common Snipe. 615 
de Académie Royale des Sciences, 1748 (published in Paris 
in 1752), pp. 345-886, pls. 15-23, gives a most interesting 
account of his observations on various birds, which might 
well be reprinted in full for the benefit of those who have 
not access to this rare volume. Hérissant observed two 
different movements when a bird opens its beak, the ordinary 
method of lowering the point of the lower mandible and, 
secondly, a tilting of the upper mandible. I give below a 
translation of the part of his paper dealing with the muscles 
employed in this action, which is particularly interesting, as 
there is a certain similarity between this description and my 
observations on the Snipe. On pp. 870-372 Hérissant 
describes the muscles used to open the bill as follows :— 
“The first of these muscles is that which I have just 
described ; when contracting, it begins to raise feebly the 
posterior extremity of the lower mandible. 
“The second is a little flat one, fleshy and almost trian- 
gular, placed obliquely behind the quadrate, which it so 
nearly touches that its anterior fibres are obliged to bend in 
order to give room for the inferior posterior angle of this 
bone. I shall call this the Triangular Muscle. 
“Tt is attached along the posterior edge of the external 
auditory meatus and to the mastoid apophysis; from there it 
descends obliquely from behind forwards, above a strong 
ligament, to which it is adherent, and passes underneath the 
posterior inferior angle of the quadrate. Subsequently it 
goes to a fleshy insertion on the external face and even on 
the edge of the apopbysis which terminates posteriorly each 
branch of the lower mandible immediately behind the arti- 
cular surface seen there. 
“The third muscle is a little longer, broader, and thicker 
than the former ; it is situated at the lateral internal part of 
the serpiform apophysis of the lower mandible. Its shape 
approaches that of a square, one of the angles of which is 
lengthened out more than the other. I shall call this the 
Square Muscle. 
“It is attached above to the lateral internal face of the 
mastoid apophysis by a flat surface, partly fleshy and partly 
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