1S85.] MR. F. K. BEODARD ON THE HEART OF APTKRYX. 189 



of a number of closely united fleshy columns. Just before the 

 junction of the left half of the valve with the muscular flap already 

 described two minute chordcB tendinece connect it witli the free wall 

 of the ventricle between the attachments of the left half of the valve 

 and the free muscular flap ; the two are fused almost immediately 

 after their origin, and form a single excessively small fibrous band 

 which is attached to a papillary muscle. 



I can find no trace of the chordce tendinece that Sir R. Owen figures 

 arising from the lower margin of the valve and inserted towards the 

 hinder end of the ventricular cavity ; the 011I3' structure at all similar 

 is the slender fibrous band which I have described as connecting 

 the valve with the free wall of the ventricle ; this structure does not 

 appear to me to be the same for reasons which I shall put forward 

 in describing the heart of Apteryx oweni. With regard to the valve 

 itself, it is not in my specimen " in some parts semitransparent and 

 nearly membranous ;" the thickness of tlie valve, which, except for 

 a small portion on the left half is entirelj' muscular, is by no means 

 less than that of any other bird with which I have had the oppor- 

 tunity of comparing it ; the very slight development of membrane 

 on the left half of tbe valve close to its origin is clearly a matter 

 of no importance, since I have found this same feature to be more 

 marked in Eupodotis and in other birds. In short, my heart of 

 Apteryx, as well as a specimen in the possession of Prof. Lankester, 

 wliich he kindly allowed me to inspect, and another preserved in the 

 Oxford Museum, present no differences of any itnportance from 

 the hearts of other birds. 



Of the heart of Apteryx oweni 1 have been able to examine two 

 examples, in both ot which the right auriculo-ventricular valve has 

 much the same structure. It only differs from that of ^. australis 

 in the presence of a stout muscular band arising from the septal wall 

 of the ventricle and attached to its free wall close to the fleshy bridge 

 which unites the free margin of the valve to the ventricular wall ; it 

 gives off" a short branch to the latter. This structure closely cor- 

 responds to the " moderator band " described by Prof. Rolleston in 

 the heart of the Cassowary ; the ckordcB tendinece which I have de- 

 scribed in the heart of A. axistrulis probably represent the upper 

 portion of the modei'ator band of A. oweni. 



I have examined a large series of hearts of birds with a view to 

 discovering if there were any deviations from the normal type in the 

 right auriculo-ventricular valve, but I can find none ; the only diffe- 

 rences at all are in the left-hand portion of the valve, which is more or 

 less membranous, and in a specimen of Evpodotis australis appears 

 to be entirely so. Gegenbaur, however, speaks of a rudimentary 

 septal flap in Sarcorhampliiis \ 



' Jen. ZeitscLr. Bd. ii. p. 380. 



