SPIDERS AND THEIR WAYS. 787 



relation to the environment. There can be little donbt that the 

 enormous tusks of the early elephants and the formidable canines 

 of many early carnivores would enable them at first to distance 

 all competitors. But the law of acceleration tended blindly 

 always in the same direction, till the old elephants seem to 

 have been weighed down by their extravagant tusks, and the most 

 highly specialized of all carnivores had canines so long that they 

 could not shut their mouths, and both speedily became extinct. 

 The law of retardation exhibits itself in the teeth of the higher 

 races of mankind in a highly inconvenient manner. The greatly 

 developed brain requires all the available room in the skull; 

 there is no space left for the attachment of muscles for a power- 

 ful jaw. Cooked food also causes a degeneracy in the develop- 

 ment of the jaw. There is constantly no room left for either the 

 wisdom-teeth or the second upper incisors ; the wisdom-teeth are 

 retarded, often cause great pain, and decay early. The second 

 incisors appear in startling and unexpected places, and often (in 

 America especially) do not cut the gum at all. Prof. Cope says 

 that " American dentists have observed that the third molar teeth 

 (wisdom-teeth) are in natives of the United States very liable to 

 imperfect growth or suppression, and to a degree entirely un- 

 known among savage or even many civilized races." The same 

 suppression has been observed in the outer pair of superior in- 

 cisors. This is owing not only to a reduction in the size of the 

 arches of the jaws, but to successively prolonged delay in the ap- 

 pearance of the teeth. In the same way men, and the man-like apes, 

 have fewer teeth than the lower monkeys, and these again fewer 

 than the insectivorous mammals to which they are most nearly 

 allied. When this difference in dentition has been established, 

 civilized man may claim to place himself in a new species, apart 

 from low savages as well as from the high apes. 



SPIDERS AND THEIR WAYS. 



By M. liMILE BLANCHAED, 



OF THE FRENCH ACADEMY OF SCIENCES. 



SPIDERS live in both hemispheres— from the torrid zone to 

 the coldest regions. Over all the world they are distin- 

 guished by their singular aspects and curious habits. The largest 

 and gayest-colored sj)ecies are found in the tropics. In cold and 

 temperate latitudes live smaller species and more tamely colored, 

 which attract attention by other titles than that of their garb. 



As classified by naturalists, the spiders compose an order of 

 the class of Arachnida. They are the Araneids, a division so 

 well characterized and perfectly circumscribed that it is sufQ.- 



