Charles F. W. McClure oe 
culty to be distinguished from the left lateral cusp. The two lateral 
cusps are attached by means of chordz tendinez to three musculi papil- 
lares which spring from the septal wall; the medial or septal cusp is, 
for the most part, attached directly to the septal wall by chord ten- 
dinexw; a few of the latter may, however, be inserted into the smallest 
of the musculi papillares which springs from the right side of the 
septum. 
The right auriculoventricular valve of marsupials has been described 
by a number of investigators, and it appears from their descriptions 
that a considerable difference exists not only as to the number of mem- 
branous cusps, but also as to the number of musculi papillares that 
may be present. These differences are clearly brought out in the fol- 
lowing table, which explains itself. 
The Right Auriculoventricular Valve of Marsupials.’ 
Family—Macropopip&. No. of cusps. No. of musculi papillares. 
Macropus (spec.) Not given. 3 
(OWEN, 66.) 
Macropus rufus. 4 2 
(WINDLE AND PARSONS, 98.) 
Dendrolagus bennetti. Not given. 4 
(BEDDARD, 95.) 
Petrogale xanthopus. 4 2 
(PARSONS, g6.) 
Petrogale penicillata. Not given. 3 
(BEDDARD, 95 ) ‘ 
Family—PHALANGERID”. 
Phascolarctos fuscus. Not given. 3 
(MARTIN, 36.) 
Phascolarctos cinereus. Not given. 20r3 
(FORBES, 81.) 
Phalangista vulpina. 4 4 
(CUNNINGHAM, 82.) 
Phalangista maculata. 4 2 
(CUNNINGHAM, 82.) 
Phascolomys wombat. Not given. 3 
(OWEN, 36.) 
Phascolomys wombat. 3 One large, one medium- 
(ROSE, go.) sized and several small. 
4 Where the number of cusps is not mentioned by the author, in all probability, 
the usual number, three, was observed. 
In the above table as well as in the following pages of this article the writer, in 
order to avoid confusion, has followed the nomenclature adopted by the authors 
referred to. 
