LAW OF SPECIALIZATION OF PHYLETIC BRANCHES 211 



the almost straight upper tusk measured about three 

 metres, and in the great species of fossil elephants, 

 the Southern Elephant, the Elephas antiquus, and 

 the Mammoth, the tusks curved either in spiral or in 

 lyre-shaped form, reached no less gigantic propor- 

 tions. We have really a right to ask ourselves of 

 what use could such cumbersome weapons be to 

 these animals. 



The bony or dermic productions designated by 

 the names of horns or of antlers, likewise show very 

 curious peculiarities in a great number of branches. 

 There is even known an Ammonite, Schlosnbachia 

 inflata of the Upper Gault, whose adult shell bears 

 on its median carina a veritable curved or even 

 spiral horn, recalling the form of a ram's horn. 

 Among Vertebrates there exist horned animals in 

 nearly all groups. A gigantic land Turtle, the 

 Miolania of the Queensland quaternary deposits, has 

 on its cranium nine bony pegs more or less pro- 

 tuberant, two of which, directed towards the side, are 

 real horns and were covered with epidermic plates 

 during the animal's life. Among the carnivorous 

 Dinosaurs or Theropods, the Ceratosaurus of the 

 higher Jurassic of California bore on the median 

 line of the nose a high, lengthy, and narrow bony 

 crest which is a true nasal horn. 



The eminent American palaeontologist, Marsh, 

 has made known to us, under the name of Ceratop- 

 sidce, a whole family of large herbivorous Dinosaurs, 

 of which the strangely horned cranium bears, in the 

 Triceratops, a small bifid nasal horn, and two enor- 

 mous bony frontal horns above the orbit, in addition 

 to a series of small parietal horns of dermic origin, 



