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Show 196 MR. A. H. GARROD ON THE [Feb. 1, forward to become part of the broad thin tendon which covers the knee and is inserted in the front of the tibia-head, the patella being situated in it, together with the long, slender, and flat tendon of the ambiens muscle, which is situated below it, running obliquely from inside and above, outwards and downwards. In many birds this muscle does not extend below the level of the femur, but ends inferiorly by blending with the vastus externus; and consequently, where such is the case, it evidently cannot, as it does otherwise, cover any of the flexors of the leg." Whether this postacetabular portion of the tensor fascia is present or absent can be found by referring to the Table (p. 199). There are not many birds in which it is very small. As the Anserine affinities of the Screamers are being discussed, it ought to be mentioned that in all the former the great pectoral flexor of the wing is peculiarly elongate, and extends upwards above the symphysis furcula, with its fellow forming a median raphe as an anterior continuation of the carina sterni. The only other birds in which this occurs are the Penguins. In the Screamers the great pectoral flexor is not large, and does not extend upwards above the middle of the furcula. In the Anseres the extensor pectoral (second pectoral) is always very long and broad, reaching the lower end of the sternum. In Chauna it does not extend nearly to the posterior margin of the sternum, and it is not bulky. Again, the muscles of the Anseres are always intensely dark in colour, whilst in the Screamer they are quite pale. In this respect the two groups differ in the same way as do the Seals and the Sirenia among Mammals. Osseous System.-The skull, being that portion of the skeleton which is least permeated with air, will receive the greatest attention on the present occasion. With reference to it Prof. Parker remarks*, "All the skull and face, except at its two ends, conforms to the lamellirostral type." Prof. Huxley also places Palamedea in his group " Chenomorphae," among the several features characterizing those birds being that " the lachrymal region of the skull is remarkably long." That such is not the case in Chauna, Prof. Parker has remarked in his article " Birds " in the Encyclopaedia Britannica j\ It may be well before proceeding further to inquire more fully into the nature of the lamellirostral type. Prof. Parker tells us that " the great embryological distinctions between the skull and face of the Geese and Fowls are, first, that in the latter the space between the periotic mass and the superoccipital cartilage is a mere chink, in the latter a persistent oval space ; and secondly, that the anterior parts of the face, viz. the praemaxillae, praevomers [maxillae], and dentaries are small and compressed in the Fowls, large and outspread in the sifting birds." A glance at the accompanying figures of the posterior surface of the skulls of a Magellanic Goose, a Derbian Screamer, and a Razor-billed Curassow will enable the reader to decide for himself which of the two groups, the Anseres or the Gallinse, the * P. Z. S. 1863. p. 514. t Enc. Brit. 8th edit, vol. iii. p. 712. |