Fig. 45 shows the ear which Hawthorne gives Donatello in the _Marble Faun_; it has been called the "Satanic" ear, because of the pointed extremities and its narrowness. The helix is rolled upon itself its entire length, giving the impression of great thickness. The anti-helix is excessively developed. Figs. 46, 47, 48 (ears of three illegitimate children at birth) show different stages of development as well as marked stigmata. Arrest of development occurs between the fourth and fifth month, owing to the trophic nerve centres being affected by the malnutrition of the mother. Fig. 49 exhibits the development of a congenital, elephantine ear in monstrosities. The resemblance to the large ear of the orang and chimpanzee is very marked. CHAPTER XIII THE DEGENERATE TEETH AND JAWS Next to the ears, the jaws and teeth (as was to be expected from the variability of these organs in allied animals) are most affected by degeneracy. This is particularly true of the vertebrates, especially mammals, as might have been anticipated from their phylogeny. At the head of the vertebrates is man; at the foot is the lancelet (amphioxus), which is perhaps most akin to those semi-vertebrates the ascidians, who, in their larval phase, are higher than when adult, and whose life-history excellently illustrates that potent phase of evolution, degeneracy. The lancelet has a spinal cord enclosed in a half-gristly canal (the notochord). It is practically destitute of a brain. The cerebral vesicle which represents this is a plain cavity without true subdivision into ventricles. There is no cranium. The eye (central in position) is a mere pigment spot with which it is able to distinguish light from darkness. The nose (behind this) is a small pit, lined with cilia, for purposes of smell. Into this the cerebral vesicle of the larval lancelet opens. The mouth is well guarded against the intrusion of noxious substances which have to pass through a vestibule richly provided with sensitive cells, resembling the taste buds of the human mouth. There is no heart. In this, as in the case of the eye, the lancelet is lower than the ascidians, the insects, crustaceans, and many molluscs. It approximates those worms which, despite a very elaborate vascular system, are destitute of a heart, the function of which is performed by contractile blood-vessels. From an embryologic and morphologic standpoint the proximate ancestor of the vertebrates may have been a free swimming animal, intermediate between an ascidian tadpole and the lancelet, and the primordial ancestor, a worm-like animal organised on a level with the star-fish. The vertebrates embryologically develop from this stage to the lampreys; thence to the cartilaginous fish (shark); to the amphibia (frog, toad, axolotl); to the reptiles; and thence to the oviparous mammals (duck-bill and echidna or spiny ant-eater); to the lemurs, and through forms like the _Pithecanthropus erectus_ to man. Mammal teeth pass, in evolution, from