328 



regular distribution of the developmental energy. Variations depend on 

 the power to vary about a mean, so that they give a false suggestion 

 of a progressive or a retrogressive developmental tendency." 



I am strongly inclined to agree with Kohlbrugge on most points ; 

 but I accept evolution, with certain [limitations, as the best working 

 hypothesis, although I regard as by no means proved, nor even prob- 

 able, that its course has been by a gradual succession of minute 

 changes. Still less do I believe that the human body is, as it were, 

 in a state of oscillation between reversive and progressive variations. 

 Finally, I can see no contradiction between evolution on the one hand, 

 and design and teleology on the other. While I shall draw from this 

 series of specimens such conclusions as seem to me justified, I hope 

 that the description will prove sufficiently accurate for those who do 

 not agree with me to make use of them also. 



The vertebra fulcralis being accepted as a starting point, 

 and the number of coccygeal vertebrae being disregarded as too un- 

 certain, the following classification resting on the number of prae- 

 sacrals and on the condition of the last lumbar, has been adopted. 



Classification. 



Class I. Spines in which the number of praesacrals is normal, 

 but in which there is an irregularity A) at the junction of the thorax 

 and loins, or B) at the junction of the thorax and neck. 



Class II. Spines in which the 26th is the fulcralis but in which 

 the 25th is not quite separated from it. 



Class III. Spines in which there are more than 24 perfectly 

 free praesacrals: A) the extra one being thoracic, B) the extra one 

 being lumbar, C) there being two extra praesacrals, one thoracic and 

 one lumbar, the latter sacralized on one side, the 27th being the 

 fulcralis. 



Class IV. Spines in which one or more praesacral vertebrae 

 are imperfectly developed: A) one or more vertebrae being fused; 

 B) the atlas being fused with the occiput; C) and D) the 24th being 

 more or less sacralized. 



Class V, Spines in which there is a praesacral too few: A) a 

 vertebra being wanting in the loins; B) in the back; C) there being 

 12 pairs of ribs, the first pair being cervical and perfect on one side, 

 the 24th being in all groups the fulcralis. 



The following is the briefest possible summary of the spines de- 

 scribed at length in the original paper. 



