Ventral.–The lower side of the body, in which lie the heart, lungs and digestive organs; and hence applied to the corresponding surface of any part or parts of the structure.
Zygodactylous (p. [10]).
CHAPTER II
ARCHAEORNITHES–NEORNITHES RATITAE–NEORNITHES ODONTOLCAE.
The Class AVES is divided by Dr. Gadow (Bronn's Klassen und Ordnungen des Thier-Reichs, Aves, Systemat. Theil, p. 299) into two Sub-classes of like value, ARCHAEORNITHES and NEORNITHES, though some writers prefer to consider the former as of equal rank only to the several subdivisions of the latter here adopted, namely, Ratitae, Odontolcae, and Carinatae (p. [25]). The question is clearly one of degree, and depends entirely on the amount of weight assigned to the various points of distinction to be mentioned below.
The Sub-class ARCHAEORNITHES is at present represented by but one member, the first undoubted fossil Bird, made known in 1861 by Andreas Wagner from the Jurassic slate formation of Solenhofen in Bavaria, and now preserved in the British Museum. This he described under the name of Griphosaurus; but as Hermann von Meyer had already bestowed the title of Archaeopteryx lithographica upon a bird, presumably identical, a feather of which had been obtained from the above system, the latter appellation has a prior claim. In 1877 a second example, now at Berlin, was procured from the same beds,[[12]] since which date Meyer's specific name has become firmly established, in place of that of macrura given by Owen to Wagner's specimen.
This very remarkable animal, about the size of a Rook, is without doubt a connecting link between Reptiles and Birds; but zoologists are practically unanimous in regarding it as an Avine form, with Reptilian affinities and probably arboreal habits.
Fig. 7.–Archaeopteryx lithographica. The Berlin specimen. (After Dames.)
The sternum was possibly furnished with a weak keel, the strong wide furcula was U-shaped, the ribs had no uncinate processes, while in all probability the coracoid and scapula made a right, or even an acute, angle at their junction, and the centra of the vertebrae of the neck and back were biconcave. The bill was short and blunt, each side of the upper jaw possessing about thirteen teeth, of which six seem to have belonged to the praemaxilla; whereas in each side of the lower jaw only three can be recognised, and those towards the anterior extremity. These teeth, conical in shape and of fairly equal size, were fixed in a regular row, in distinct sockets. The fibula and tibia did not coalesce, the latter exceeding the metatarsus in length; the toes were four in number, with two, three, four, and five phalanges respectively, ending in claws, the hallux being directed backwards. The manus had three free digits, and apparently three free metacarpals; the pollex consisted of two joints, the index of three and the third finger of four, while each had a strong hooked claw at the tip. The hand was furnished with six or seven well-developed primaries, attached to the third metacarpal and the second and third digits, the number of secondaries being ten. The long Lizard-like tail had no terminal pygostyle, but was composed of about twenty-one free post-sacral vertebrae, of which the first twelve each bore a pair of large feathers, similar to those of the wing, with the inner webs broader than the outer, and with decided shafts.[[13]]