organ, forming a levator ingluviei. A portion of the cucullaris also directs itself towards the patagium, and in most Passeres and in parrots, Pici, and Upupa forms a special cucullaris propatagialis, joining the tensor longus tendon. The pars cervicalis of the cucullaris arises from the dorsal edge of the neck, and is inserted near or in common with the other part. In many birds (e.g. Anseres) a slip is given off from this which supplies the humeral pterylon. It is termed the cucullaris dorso-cutaneus. Rhomboideus Externus.-This muscle arises tendinously, the width of the tendinous part being about the same as that of the muscular part, from the last cervical and from the dorsal vertebræ ; it is inserted fleshily along the whole length of the scapula. The muscle varies but slightly; the origin is more or less extensive, and the vertebræ from which it arises are not always the same. Its insertion is not always limited to the scapula, but sometimes extends on to the furcula. In Casuarius and Apteryx the muscle arises from the ribs. Rhomboideus Profundus.-This muscle also arises tendinously from the neural spines of the dorsal vertebræ, or from both dorsal and cervical. Its origin sometimes extends as far back as to the ilium. It is inserted into the scapula below the last. In Casuarius and Apteryx this muscle arises from the ribs. The rhomboideus profundus is occasionally divided into two distinct parts; in Megalama there are three distinct divisions. Serratus Superficialis.-This muscle is divided by FÜRBRINGER into three parts, of which two are always present, while the third is sometimes absent. This is the pars metapatagialis. The pars anterior arises from one or more ribs on the boundary line between the cervical and dorsal series. It is attached to the scapula along the ventral border, but, quite exceptionally, in Rhea on to the dorsal border. The pars posterior springs from a varying number of dorsal ribs, and in several birds (e.g. Rhamphastos) it, with the pars anterior, which can hardly be separated as a distinct muscle, springs from a considerable number of ribs-five in the case referred to. Ꮐ It has generally a broadish insertion on to the scapula, but in Meiglyptes, many Passeres, &c., it is attached merely to the extremity of that bone. The pars metapatagialis is absent in ratites (except Apteryx), humming birds, and a few others. It springs from 1-4 ribs, and is inserted on to the metapatagium. Serratus Profundus.—This muscle is highly developed in Struthio and Casuarius, less so in other struthious birds and in the Carinates. It arises from a variable number of cervical and dorsal ribs, and it passes backwards (in the contrary direction, therefore, to the serratus superficialis) to be inserted on to the scapula. Patagialis.-This muscle, concerned with the folding of the patagial membrane, is present in all birds except the struthious. It arises from the clavicle and from the tip of the scapula, is sometimes divided into two muscles from the start, and sometimes arises as a single muscle, which immediately divides into two tendons, the tensor patagii longus and the tensor patagii brevis. Exceptionally the former may be absent. In a specimen of Crex pratensis the representative of tensor patagii longus was found by GARROD to be simply the biceps slip, a muscle that will be treated of presently. The size and importance of this muscle vary considerably; it is largest in the parrots, where, indeed, it is uncertain whether a part of the deltoid has not been converted to a similar function. This matter, however, is dealt with under the description of that family. The tensor patagii longus always ends in a single tendon which runs along the anterior margin of the patagium and is inserted on to the metacarpal. It is usual for the middle part of this tendon to be of a more fibroid character and of a yellowish colour, contrasting with the steely and typically tendinous aspect of the other tendons arising from the tensores. Very commonly the entire tensor muscle is reinforced by a tendinous or muscular slip from the pectoralis, and sometimes there is a separate slip to each of the G. BUCHET, 'Première Note sur l'Appareil Tenseur,' &c., C. R. Soc. Biol. 1888, p. 328. two tensores. It is also very general for one of the two tendons, or for both before their division, to be attached by a tendinous slip to the deltoid crest of the humerus. The tensores patagii are of considerable use in classification. But it must be admitted that they are apt to vary greatly from genus to genus. The variations chiefly concern the more or less complicated condition of the tendons of the brevis. The simplest condition is seen, e.g., in Rhamphastos Cuvieri, where the tendon is single and is attached below to the tendon of origin of the extensor metacarpi radialis. A further degree of complication is seen in, e.g., a cuckoo, where the single tendon gives off, near to the fore arm, a slip running obliquely wristwards, which is attached to the tendon of the extensor metacarpi radialis. In the limicolous birds the main tendon is usually divided from the first into two, of which the anterior has the wristward slip, already referred to; in those birds and many others there is the further complication of a band of tendinous fibres which arise at the junction of the wristward slip with the fore arm, and pass obliquely forwards and upwards to be inserted on to the tendon of the longus. This slip is termed, in the following pages, the 'patagial fan; it is frequently of a fanlike form. The tendon of the tensor patagii brevis has not always the regular form that it has in the types that have been already selected for illustration. In the tinamou, Rhynchotus, for instance, the tendon is a diffuse fascia spreading out over the greater part of the patagial membrane; in other birds, e.g. storks, it is a broad, rather diffuse band, as a rule with a thicker edge or edges. A peculiar condition of the tendons of the brevis characterises the auks, some gulls, and at least one limicolous bird. In them (see below) one or two delicate tendons arise from the longus tendon near to the insertion thereon of the patagial fan, and run obliquely backwards and downwards to be attached on to the dorsal surface of the fore arm-the reverse side, that is to say, to that to which the other tendons which together make up the tensor patagii brevis are attached. In some birds, e.g. certain passerines, the tendon of the tensor longus is reinforced by a muscular slip ending in a tendon which is derived from the cucullaris muscle. Another muscle which is also related to the patagialis in an analogous way has been termed the 'biceps slip' (q.v.) Anconæus Longus.-This muscle arises from the neck of the scapula alone, by a head which is entirely tendinous or partly muscular, or in addition from the edge of the scapula, a little further away from its junction with the coracoid, by a tendinous head. It is inserted by a broad tendon on to the T.P.L. Bi -T.P.B E.C.R. FIG. 49. TENSORES PATAGII OF Phænicopterus. T.P.L, tensor patagii longus; T.P.B, tensor patagii brevis; Bi, biceps elbow joint. Sometimes there is an accessory head from the humerus, which in this case arises, as a rule, in common with the tendon of insertion of the posterior latissimus dorsi. In Palamedea this head is double, the two halves being united by cross tendinous threads. On the whole the humeral head is characteristic of GARROD'S Homalogonatæ and not of the Anomalogonatæ ; but there are exceptions on both sides. The breadth of the humeral head varies greatly; it is sometimes reduced to a thin thread. - Triceps. This muscle springs from the greater part of the humerus fleshily by two heads, of which one-that from the tuberculum minus-is often tendinous. The name triceps, be it observed, has been given to the muscle on the understanding that the last-described muscle is a part of it. Their tendons of insertion join. Expansor Secundariorum.'—This extraordinary muscle appears to be partly a skin and partly a skeletal muscle. A bundle of non-striated fibres arises near the secondary feathers of the arm and ends in a tendon. This is occaband of striated fibres arising sionally reinforced by a from beginning of ulna. The long tendon is inserted in various ways. The typical condition (termed by GARROD 'ciconiine') is for it to be inserted into the middle of a ligament running from the scapulo-coracoid to the sternocoracoid articulation. Other modifications occur among the gallinaceous birds (q.v.), &c. The muscle is totally absent in Struthiones, Sphenisci, Alcæ, Psittaci, the majority of PicoPasseres, and in a few species of groups where it is usually present. Sterno-coracoideus. This muscle, wanting only in the Macrochires, runs from the anterior lateral border of the sternum to the adjoining region of the coracoid. The muscle shows every stage between a single muscle and a completely double one. It is double, for example, in Casuarius. In Struthio, Chauna, and some other birds where there is but one sterno-coracoid, it is the homologue (according to FÜRBRINGER) of the deeper section of the double muscle. Scapulo-humeralis Anterior.-Runs from the beginning of the post-glenoidal region of the scapula to the beginning of the dorsal surface of the humerus. It is a muscle which is frequently absent. FÜRBRINGER failed to find it in Struthiones, Sphenisci, Fregata, Chauna, Columbæ, Pterocles, Chunga, Bucorvus, &c, Scapulo-humeralis Posterior.-Contrary to the last this is a large muscle and is never absent. It arises from the GARROD, On the Anatomy of Chauna derbiana,' &c., P. Z. S. 1876 p. 193, &c. |