at the bottom of lakes and rivers, and is obliged, like the Ichthyosaurus, to be continually rising to the surface to breathe air.[1]
Here then we have a race of animals that became extinct at the termination of the secondary series of geological formations, presenting, in their structure, a series of contrivances, the same in principle, with those employed at the present day to effect a similar purpose in one of the most curiously constructed aquatic quadrupeds of New Holland.[2]
Paddles.
In the form of its extremities, the Ichthyosaurus deviates
from the Lizards, and approaches the Whales. A large
a quadruped clothed with fur, having a bill like a duck, with four webbed feet, suckling its young, and most probably ovoviviparous: the male is furnished with spurs.—See Mr. R. Owen's Papers on the Ornithorhynchus Paradoxus, in the Phil. Trans. London, 1832, Part II. and 1834, Part II. See also Mr. Owen's Paper on the same subject in Trans. Zool. Soc. Lond. Part III. 1835, in which he points out many approximations in the generative and other systems of this animal to the organization of reptiles.
- ↑ In both these animals there is superadded to the ordinary type of bones in quadrupeds, an enlargement of the coracoid bone (c,) and a peculiar form of sternum, resembling the furcula of birds. In Pl. 12, Fig. 1, a. represents the peculiar sternum or furcula; b. b. the clavicles; c. c. the coracoid bones; d. d. the scapula; e. e. the humeri; f. g. the radius and ulna. At Fig. 2, the same letters are attached to the corresponding bones of the Ornithorhynchus.
The united power of all these bones imparts to the chest and paddles peculiar strength for an unusual purpose; not so much to effect progressive motion (which, in the Ichthyosaurus, was produced with much greater facility and power by the tail,) as to ascend and descend vertically in quest of air and food.
- ↑ The Echidna, or spiny Ant-eater, of New Holland, is the only known land quadruped that has a similar furcula and clavicles. As this animal feeds op Ants, and takes refuge in deep burrows, this structure may be subsidiary to its great power of digging. A cartilaginous rudiment of a furcula occurs also in the Dasypus; and seems subservient to the same purpose.
