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- 

 ndides." 



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 Dinornis and their 

 alHes. 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 Mau and the Rabbit, with 

 some Observations on the Fossa Ovalis. By E. Ray 

 Lankester, M.A.J F.E..S., Jodrell Professor of Zoology 

 in University College, London'. 



[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 to rest chiefly upon the 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 cam 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. lUe revera 



1 I am indebted to Mr. J. J. Quelcli, B.Sc, lately my assistant, and now one of 

 the staff of the British Museum, tor aid in making the drawings and dissections 

 upon which this memoir is based. 



