270 Proceedings of the Royal Society of Edinburgh. 
afforded by the case recorded by Kaau Boerhaave, to which I 
alluded in my former paper, and they support the opinion I ven- 
tured to throw out in that communication, that the supracostal 
muscle described by Mr John Wood (Proc. Roy. Soc. London , June 
15, 1865), is homologous with the pectoral end of the mammalian 
rectus. 
During the past year, Mr Wood has described another specimen of 
the supra-costal muscle ( Proc . Roy. Soc. London , May 23, 1867) 
which passed from the third rib upwards to the first rib and cervical 
fascia ; Dr Roberts ( Liverpool Medical and Surgical Reports , Octo- 
ber 1867), one which extended from the fourth to the first rib; and 
Bochdalek, Jun. (Yirchow’s Archiv. 18th November 1867), under 
the name of M. supra-costalis anterior, has described and figured 
one, which also passed from the fourth to the first rib; but by 
none of these anatomists is any reference made to the proba- 
bility of its being homologous with the pectoral end of the mam- 
malian rectus. 
The specimens which I have now recorded apparently corre- 
spond to the supra-costal muscles of these writers ; and the arrange- 
ment more especially of the first, in which the muscle extended as 
low as the fifth rib, and was separated from the rectus only by the 
breadth of that rib, justifies me, I think, in the conclusion I have 
come to respecting the homology of the muscle. 
