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Show 340 MR. A. H. GARROD ON THE [Apr. 4, modification of which, in the genus Ceryle among the Alcedinidae, has been described and figured by Dr. Cunningham in the Society's ' Proceedings'*. This, by the way, I may mention, I have had the opportunity of fully verifying. Meckel, in his ' General Treatise on Comparative Anatomy,' tells usf that he found it at its minimum of development in the Gallinae, the Goose, and the Cormorant. In a specimen of Sula fusca, as well as in Phalacrocorax carbo, it is present, but extremely small, I find. It is entirely absent in Plotus anhinga, the longus colli posterior (cervicalis ascendens, Meckel) entirely ceasing at the lower margin of the axis vertebra, in the tendon above described. There are other myological features deserving of special notice in the thoracic and crural regions of the Darters. The great pectoral muscle is composed of two independent layers : - a superficial large one, arising from the inferior border of the sternum, its carina, and from the outer border of the furcula ; and a deep one from the upper two thirds of the deeper part of the carina, superficial to the pectoralis secundus, and from the symphysial half of the outer border of the furcula. The superficial layer is inserted by a broad linear attachment to the pectoral ridge of the humerus, whilst the deep layer ends in a rounded tendon which commences at the axillary margin of the triangular muscle, with which it is associated, and receives the fibres of the remainder of the muscle in its course to its attachment into the lower end of the pectoral ridge of the humerus, beyond the insertion of the lowest fibres of the superficial layer. In Plate X X V I I . this arrangement is clearly indicaled. A condition exactly similar to this is observed in Phaethon, Pelecanus, Sula, the Cathartidae, all the Storks, and the Petrels, and in no other birds as far as I a m aware. In Phalacrocorax it is not easily recognized. As in Phalacrocorax and Phaethon, but not in Sula or in Pelecanus, the biceps muscle of the arm sends a fleshy slip to the middle of the patagial tendon of the tensor patagii longus (Plate X X V I I . b.s). N o trace of the expansor secundariorum'^. muscle could be detected. As in all the other Steganopods, the tensor fascia of the thigh does not cover the biceps cruris in the least. The ambiens is of fair size ; it deeply grooves the large ossified patella; and some of the fibrous ligament overlapping this groove shows traces of ossification ; so that in aged birds the groove may be converted into a foramen, as is always the case in Phalacrocorax, where the thus formed foramen is far from superficial (vide Plate XXVIII. figs. 5, 6, & 7). In a specimen of Pelecanus rufescens the patella was not ossified. The semitendinosus is very large, composed of parallel fibres, and without any accessory head developed to join it. The femoro-caudal also, as in all other true Steganopods, lacks an accessorius; it closely * P. Z. S. 1870, p. 280. t French edition, Paris, 1829-30, vol. vi. p. 11. X Vide ante, p. 193. |
