OCR Text |
Show 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 Dinornis 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 N e w Zealand. This memoir will be printed entire in the Society's 'Transactions.' The following papers were read : - 1. O n the Valves of tbe Heart of Ornithorhynchus paradoxus compared with those of M a n and the Rabbit, with some Observations on the Fossa Ovalis. By E. R A Y L A N K E S T E R , M.A._, F.R.S., Jodrell Professor of Zoology in University College, London1. [Received May 30, 1882.] (Plates XXXVHI.-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 Mammalia, appears to rest 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 structure 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 w o r c [ s : - " Ostium venosum valvula clauditur simplici, semilunari. Cuvierus earn 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. Hie revera 1 I a m indebted to Mr. J. J. Quelch, B.Sc, lately m y 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. |