374 SCOTT. [Vol. V. 



other exceptions might be cited. With regard to the mode of 

 reduction of the vertebral column, fossils are not well adapted 

 to throw light upon the question, because specimens in which 

 the vertebral column is at all completely preserved are very 

 rarely found. So far as the evidence goes, however, it appears 

 to favor Fiirbringer's position, that reduction is from behind 

 forward, and that the changing numbers of the dorso-lumbar 

 vertebrae are due to a shifting of the limb-girdles. The early 

 forms of mammals in which the number of trunk-vertebrae is 

 known, have, for the most part, a larger number than have their 

 modern representatives, and a very general characteristic of 

 these ancient forms is their very long, stout, and well-developed 

 tails. This evidence is, however, too imperfect to be at all con- 

 clusive, and whatever may be true of the mammals, Parker's 

 results seem to show that in the turtles, suppression of vertebras 

 may take place in the cervical region without affecting the 

 position of the limb-girdles or the number of the dorso-lumbar- 

 sacrals. Baur has recently published (No. 2) the results of his 

 studies upon the spinal columns of certain lizards, crocodiles, and 

 serpents, in which he comes to the conclusion that intercalation 

 does occur. " My opinion is that in the increase of the number 

 of segments, not only in vertebrates, but also in invertebrates, 

 intercalation has played a much greater role than is generally 

 admitted" (p. 335). The evidence adduced is not, however, 

 altogether conclusive. 



8. Increased size and weight of body of course entail increased 

 thickness and massiveness of the bones, with much more prom- 

 inent and rugose processes for the attachment of muscles and 

 ligaments ; but the effect upon the skeleton is much more pro- 

 found and far-reaching than this, as will appear from a com- 

 parison of the Proboscidea, the Dinocerata, and the equally huge 

 perissodactyl, Titanotherium, which are about as widely sepa- 

 rated from one another as three ungulate lines well can be. Little 

 is known about the phylogeny of the elephants, but so far as 

 the other two series are concerned, their earlier members are in 

 many respects less alike than the later ones, while in the final 

 members of all three lines we find many and striking resem- 

 blances. The neck is shortened, the trunk very long, and the 

 anterior dorsal vertebras rendered very heavy, with much elon- 

 gated spines to support the massive head, which is greatly en- 



