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Show 188 MR. W. K. PARKER ON STEATORNIS CARIPENSIS. [Apr. 2, an essentially Reptilian "root," yet the various parts are marvellously transformed, and the bird itself has gained a far higher structural and physiological level than that of even the highest and most modern Reptile. Here, however, in Steatornis, we find the ancient structures built up within the modern; it is not a perfectly typical bird, but is composite, so to speak, a type made of things new and old. The Singing-birds, including, of course, the large Crows, have, more than any other birds, put away the old leaven of the low Reptilian nature that they started with; yet in them, as I have shown, the old materials are sometimes built up into, but hidden by, the transformed, newer parts. But here, in this bird, the hinder part of the pre-sacral chain of vertebrae has its articulations of the opisthoccelian kind, as in Archaic Reptiles. Its palate, also, has just the same degree of Desmogna-thism as the Green Turtle (Chelone viridis); and it has more free cervical ribs than any other known bird. Its tarso-metatarsus is but that of an Ornithoscelidan Reptile, just masked by ankylosis of certain parts; it is in an arrested condition as compared with that of any Passerine bird. All birds living, both Ratitae and Carinatae, come nearer the Amphibia than any kind of existing Reptiles in the foundations of the cranial superstructures ; the " parasphenoid " is very large and Ichthyopsidian in all these supra-reptilian types. But the Oil-bird, like a few more of the Carinatae,-Muso-phagidae, Procellariidae, &c,-has in its fore palate the triradiate remnant of the fore part of the Amphibian palato-quadrate; it clearly shows, in the adult, the "ethmo-," "pre-," and "post-palatine " bars. The conclusion to be drawn from facts of this kind is, surely, not that Birds are to be imagined as arising from the Reptiles, proper- the cold-blooded " Amniota"-either by the utilization of sudden " sports," or by a slow, secular adaptation of Reptilian structures to the necessities of a flying creature, this flying creature becoming hot-blooded, quick-tempered, intelligent, vocal, and loving. Rather, it seems to me, to point out that the origin of the Bird must be sought for, by the "scientific imagination," among low and quasi-larval forms, similar to those with which we are acquainted in the larvae of existing Amphibia and Fishes, and similar to, and near relations of, other low Chordata, that gave rise to the Reptiles. The low and simple types from which we may suppose the Mammalia to have arisen could not have been so nearly related as those from which, by the mystery of transformation, the Reptiles and Birds had their origin. Although hot-blooded, the lowest kind of Mammals-the Monotremes- are in some parts of their organization on a level with such Archaic Reptiles as the Ichthyosaurus (for example in their shoulder-girdle); yet in the formation of their mouth and middle-ear they are quite unlike both Reptiles and Birds; and show in a |
