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Show 1890.] ANATOMY OF PODICA SENEGALENSIS. 427 there is a distinct division of the pectoral tract such as occurs Rails. The inner branch is much broader than the outer, and ends abruptly, as _ figured by Nitzsch in Rallus aquaticus, a short way below the wing ; the inner branch of the pectoral tract is if anything rather broader nearer to its free extremity than at its origin; it is 1| inches long; the outer branch of the pectoral tract is wider at first, though not so wide as the inner branch. The humeral tracts are very strong, and certainly more than two feathers wide (2-6). In almost every point, therefore, the pterylosis of Podica senegalensis differs from that of its American ally. As regards other external characters, I find that there is a close agreement between the Neotropical and African forms. The oil-gland is distinctly tufted. The contour-feathers have no aftershaft. There are 18 rectrices. I count 21 remiges. It is important to notice that the 5th cubital remex is not wanting [see Wray, 10 ; Sclater, 9]. The pterylosis of Podica is so different from that of Heliornis, that we must assume one of two things : either that Nitzsch's description is wrong, or that the pterylosis-at least in this group-has not the significance that is frequently attached to it. As a mere question of probability, it does not appear to me to be necessary to pin our faith too firmly to the data of pterylography. And I sbould be disposed to regard Nitzsch's description of Heliornis as likely to be right. § 2. Myology \ The pectoralis primus muscle is separable into two layers, which are even to be distinguished by a slight difference of colour; the separation is effected by a tendinous sheet. The muscle arises from the keel of the sternum and from its outer margin behind the third pectoral and alongside of the second pectoral, and from the hinder part of the sternum which is not reached by the second pectoral; it has also an origin along a line running parallel to but of course below the uncinate processes from the ribs2. Pectoralis secundus: this muscle is large and extends nearly to the end of the sternum; it has the usual bipinnate form. The scapulo-humeralis is a broadish band of muscle underlying the tendon of the biceps. In the accompanying sketch (Plate X X X I X . fig. 1) is illustrated the patagial muscles of the bird. 1 I have in this section principally confined myself to those muscles which are known to be of use for systematic purposes. 2 Fiirbringer [4, p. 417 and note] denies that this extrasternal portion of the pectoral muscle springs from the ribs ; it takes its origin, according to him, from the " parasternal fascia " which covers the stern o-costal muscles. Nevertheless I cannot but think that in Podica senegalensis the origin is actually in part from the ribs themselves. |