1882.] ON THE HEART OF ORNITHORHYNCHUS PARADOXUS. 549 
toed. On the other hand, I have been quite unable to detect even 
a trace of it in some such birds, as e. g. Rhea, Tetrax, and Peleca- 
noides.” 
Prof. Owen, C.B., F.R.S., F.Z.S., read the twenty-fourth of his 
series of memoirs on the extinct birds of the genus Denornis and their 
allies. The present memoir contained the description of the head 
and two feet with the dried integuments attached, of an individual 
of a species of Dinornis, proposed to be called D. didinus, which 
had been recently obtained from a cavern or fissure near Queenstown, 
in the South Island of New Zealand. 
This memoir will be printed entire in the Society’s ‘ Transactions.’ 
The following papers were read :— 
1. On the Valves of the Heart of Ornithorhynchus paradoxus 
compared with those of Man and the Rabbit, with 
some Observations on the Fossa Ovalis. By EH. Ray 
Lanxester, M.A., F.R.S., Jodrell Professor of Zoology 
in University College, Londen’. 
[Received May 30, 1882.] 
(Plates XXXVIII.-XLI.) 
The statement current in text-books of Comparative Anatomy to 
the effect that in Ornithorhynchus paradoxus the right auriculo- 
ventricular valve is “ fleshy,” and therefore in some degree similar to 
that of Reptiles and Birds and different from that of other Mam- 
malia, appears torest chiefly uponthe statements and figures of Meckel, 
published in his Monograph of the Anatomy of the Duck-bill, though 
Cuvier, Owen, and Gegenbaur have also made observations on the 
subject. No anatomist appears to have published any drawing of 
the heart of Ornithorhynchus since Meckel in 1828; and no 
figure has ever been given of the interesting points of struc- 
ture presented by that heart which is in any sense adequate. The 
figure of the opened heart given by Meckel, and intended to show 
the fleshy auriculo-ventricular valve, is simply unintelligible owing 
to the absence of both shading and colour. 
Meckel describes the right auriculo-ventricular valve in these 
words:—‘*‘ Ostium venosum valvula clauditur simplici, semilunari. 
Cuvierus eam nonnisi concavo ventriculi pariete respondere dicens, 
minus perspicue loqui videtur, quum uterque, et anterior s. dexter, 
et posterior s. sinister, a septo formatus, convexi sint.  Ille revera 
1 T am indebted to Mr. J. J. Quelch, B.Sc., lately my assistant, and now one of 
the staff of the British Museum, for aid in making the drawings and dissections 
upon which this memoir is based. 
