HUMAN RESEMBLANCES TO LOWER LIFE. 13 



small plate of cartilaginous gristle. Traced backwards to the ante- 

 cedents which it owns, this fold is seen to represent the third eyelid 

 in a degraded and deteriorated condition. From its highly developed 

 shutter-like function in birds, where it sweeps over the eye-surface 

 and cleanses the globe from foreign bodies, or from its development 

 amongst lower quadrupeds, to the degradation it exhibits even before 

 the sphere of humanity is approached, many links of the chain may 

 be wanting in truth. But for the mind of the anatomist there remains 

 only one natural explanation of the occurrence of the useless fold in 

 the corner of the human eye. Like the rudimentary ear-muscles, it 

 carries us in imagination to a far back past, when, in the pre-human 

 ancestry, the third eyelid possessed functions as important as that 

 exhibited by its representative in the bird to-day. 



The teeth of animals form a series of structures, subject, as ' 

 even the tyro in zoology knows, to literally immense variations, 

 which bear, as a rule, a relation to the habits of life of their posses- 

 sors. Man's teeth are undoubtedly peculiar in that they form a con- 

 tinuous series, and are not separated throughout their extent in 

 either jaw by an interval, such as we see very familiarly in the mouth 

 of a horse or rat. It is true that man shares this peculiarity with a 

 little lemur called Tarsius, and with an extinct quadruped the Anoplo- 

 therium ; this fact serving naturally to diminish somewhat the 

 special character of the human teeth-array. The "eye-teeth," or 

 " canines " of humanity, although not specially prominent, are yet 

 sufficiently developed to prove that they have assumed their present 

 place in the jaw only by protest, as it were, and that at no very 

 remote period they were much more obtrusive than now. In the 

 apes, we see these teeth highly developed, reminding us of their 

 prominence in the carnivorous tribes. So also, when man sneers, he 

 uncovers his upper canine of one side, after the fashion of the enraged 

 dog, and employs similar muscles for the display of the tooth. Mr. 

 Darwin is, therefore, speaking within the bounds of a scientific 

 philosophy when we find him saying that a sneer reveals the animal 

 descent of man ; "for no one," he continues, "even if rolling on the 

 ground in a deadly grapple with an enemy, and attempting to bite 

 him, would try to use his canine teeth more than his other teeth. 

 We may readily believe from our affinity to the anthropomorphous 

 (or manlike) apes that our male semi-human progenitors possessed 

 great canine teeth, and men are now occasionally born having them of 

 unusually large size, with interspaces in the opposite jaw for their re- 

 ception. We may further suspect," concludes Mr. Darwin, " notwith- 

 standing that we have no support from analogy, that our semi-human 

 progenitors uncovered their canine teeth when prepared for battle, 

 as we still do when feeling ferocious, or when merely sneering at or 

 defying some one, without any intention of making a real attack with 



