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Show 142 MR. F. E. BEDDARD ON THE [Mar. 18, 3. Notes on the Anatomy of the Condor. By FRANK E. BEDDARD, M.A., Prosector to the Society. [Eeceived March 4, 1890.] Iii the present communication I wish to direct attention to the structure of the trachea and of the heart in the Condor. Certain interesting statements by Prof. Gegenbaur l concerning the structure of the right auriculo-ventricular valve made me specially anxious to study this bird, which the death of a specimen at the end of last year has enabled me to do. In the trachea I refer to one or two structural points of slighter importance. 1. Heart. The general structure of the right auriculo-ventricular valve in the Bird's heart is well known ; there are, however, some discrepancies among the descriptions of the corresponding valve in tbe Crocodile, with which it is universally agreed that that of Birds must be compared. Gegenbaur's description of this valve in the Crocodile is very detailed, though unaccompanied by figures. The valve consists of two halves, a muscular and a membranous ; the former borders the anterior and outer margin of the atrio-ventricular orifice, the latter the septal margin of the same. " The hinder lateral part of the ventricular cavity appears spongy from the presence of a number of fleshy trabeculae : of these one is of importance, which runs from the anterior ventricular wall upwards and backwards to the jutting-out muscular valve to be inserted in the neighbourhood of its free margin. This muscular trabecula is not in any way distinguished from the neighbouring ones ; it is, indeed, less conspicuous, but it is constant (so far as the small number of hearts examined [4] enable me to say). It is more conspicuous in the Crocodile than in the Alligator, and is readily seen. It forms a fleshy bridge from the muscular margin of the ostium to the lateral ventricular wall." In comparing these arrangements with that which characterizes the Bird's heart, Professor Gegenbaur duly calls attention (p. 380) to the absence in the latter group of all traces of the membranous valve except in the Condor, which is described as follows:- " Only in the heart of Sarcorhamphus do I find a peculiarity which has interest in this connection. From the anterior origin of the muscular valve on the septum ventriculorum a fold runs backwards, which is formed by a thickening of the endocardium. The fold runs obliquely backwards and downwards and crosses in its direction the margin of the muscular valve. The course of this fold corresponds to the line of origin of the membranous valvular flap of the Crocodile; I think it reasonable therefore to regard it as a remnant of the structure which is further developed in the Crocodile." 1 " Zur vergleichenden Anatomic des Herzens," Jen. Zeitsch. Bd. ii. (1866) p. 365. |
