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Show 1885.] PROF. LANKESTER ON THE HEART OF APTERYX. 239 T. limula, Hilgendorf, from Senegambia, the postfrontal crest less distinctly developed near the lateral epibranchial teeth, behind which, in the males, are indications of two other teeth. 7. On the Heart described by Professor Owen in 1841 as that of Apteryx. By E. R A Y LANKESTER, M.A., LL.D., F.R.S., Jodrell Professor of Zoology in University College, London, Fellow of Exeter College, Oxford. [Received February 19, 1885.] When busy some three years ago with the examination of the right cardiac valve of Ornithorhynchus and Echidna, I was naturally anxious to examine the similar valve of Apteryx, which had been stated by Sir Richard Owen to present a divergence from the character which it usually presents in Birds, and instead of being purely muscular as in all other Birds, to possess membranous areae and chordae tendineae. Sir Richard Owen gives the following account of this valve in his paper published in 1841, in the 'Transactions ' of this Society (vol. ii. p. 272) :- " The principal deviation from the ornithic type of the structure of the heart is presented in the valve at the entry into the right ventricle (pi. Iii. g. fig. 3). This is characterized in birds by its muscularity and its free semilunar margin. In the Apteryx it is relatively thinner, and in some parts semitransparent and nearly membranous ; a process moreover extends from the middle of its free margin, which process is attached by two or three short chorda; tendinece to the angle between the free and fixed parietes of the ventricle. W e perceive in this mode of connection an approach in the present bird to the mammalian type of structure analogous to that which the Ornithorhynchus, among Mammalia, offers, in the structure of the same part, to the class of birds; for the right auricular ventricular valve in the Ornithorhynchus is partly fleshv and partly membranous. The dilatable or free parietes of the right ventricle were about -j^th of an inch in thickness, those of the left were -g- th of an inch thick." I was fortunately able to gratify m y curiosity with regard to the heart of Apteryx by the dissection of a specimen preserved in spirit, which I owe to the courtesy of Mr. Cheeseman. I was not a little astonished to find that the right cardiac valve of m y Apteryx was totally different from that described by Owen, and so far from presenting any membrane or chordae tendineae, exhibited the normal structure of the right cardiac valve in birds; in fact was a purely muscular lobe. I put the matter by at that time, and was reminded of it a few weeks since by Mr. Beddard, who told me that he had obtained a precisely similar result to my own from the examination of a specimen of Apteryx which had recently come into his possession. Mr. Beddard further told me that he had taken an opportunity |