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Show 322 DR. GADOW ON THE ANATOMY OF PTEROCLES. [Mar. 21, The four other muscles are well developed in most birds, as Prof. Garrod has stated over and over again, and as the dissection of any fowl will show. 4. " The special relation of the tendon of the ambiens (when present) to the fibular head of the flexor perforatus secundus tertii digiti." The distal end of the ambiens muscle, when typically developed, always forms the continuation of one of the heads of the m. flexor perforatus dig. n. et in. 5. " The presence of lumbricales in the foot.'' The muscle which Mr. Haswell takes to be the representative of the lumbricales muscles of mammals has not " hitherto escaped the notice of anatomists," and it is not " peculiar to the Pigeons," since it is also present in many other birds, e. g. the Batita?, and has been described by Meckel, although he gave no name to it, in his ' System der vergleich. Anat.' iii. p. 388, and in his 'Archiv fiir Anat. u. Physiol.' pp. 278 & 279. With regard to the muscles of the leg, I am unable to point out any typical differences between Sand-Grouse, Fowls, and Pigeons. The absence of the m. flexor hallucis longus in Pterocles is of no importance, as this muscle is generally absent in birds which have no hallux or only a small one, and, moreover, as the absence of this toe itself affords no family character. Of course there are many points, e. g. the mode of origin and the arrangement of the tendons of the muscles, and even the absence of the m. plantaris and of the m. peroneus profundus, which are noteworthy in Pterocles; but all these things are variable, and give us no characters which hold good throughout the Gallinaceous or the Columbine group. It is the same with the m. ambiens : this muscle is present and well developed in Pterocles and most probably in all the Rasores ; in the Pigeons its presence is variable. Of all the other muscles connected with the leg, there is none that shows any practical difference between Sand-Grouse, Pigeons, and Fowls, and even (if we include them in our comparison) the Plovers. On the whole, however, the myology of Pterocles indicates that it is more nearly allied to the Pigeons than to any other group of birds. VISCERA. "The trachea is cartilaginous; and it has at its bifurcation what the Grouse is bereft of, viz. a pair of laryngeal muscles, as in the Pigeons, Taleg alia, and Plover " (Parker). The crop (ingluvies) of Pterocles is a simple dilatation of the anterior and lateral walls of the oesophagus, without any constriction in the middle line, although it is broader than long. Its walls are very thin on its anterior parts, and show longitudinal folds and glands ; the dorsal part, the prolongation of the dorsal half of the oesophagus, is thicker and slightly muscular, the external sheath consisting of transverse, the inner one of longitudinal smooth muscular fibres. In the Pigeons the crop is different. It consists of two lateral and symmetrical dilatations of the lateral walls, whilst the middle part is simply the continuation of the oesophagus, slightly widened |