308 THOMAS DWIGHT ON 



H-3) . In no case is there an increase in number of the praesacrals, which should be 

 expected if this were an archaic manifestation. In half the cases the number of prae- 

 sacrals is nonnal, in three the last is partially sacralized, and in two, the most perfect 

 cases (267 and 202), there is a praesacral too few. Turning to the literature of cervical 

 ribs, as given by Gruber to 1869 and continued by Pilling to 1894, I find but a single 

 case of unmistakable cervical rib with an increase in the number of praesacral vertebrae, 

 that of Leveling (l787) . Unfortmiately in most cases the vertebral formula is not given ; 

 still in many it is reported normal, and in a few reduced. To this case should perhaps be 

 added the two cases of Leboucq, in which there was an additional cer\acal vertebra with a 

 cer\dcal rib on the 8th, and the case reported by Lane, already mentioned. Above aU 

 there is Rosenberg's spine with 26 praesacrals and 15 ribs, the first being a cer\ical one. 

 This spine, indeed, is a most satisfactory one from Rosenberg's point of view ; Init, admit- 

 ting its authenticity, it stands alone ; the overwhelming mass of observation is just the other 

 way. Thus there are two spines, Levehng's and Rosenberg's, with cervical ribs and an 

 increase of praesacral vertebrae not in the cervical region. On the other hand there are 

 several instances of reduction of the number of praesacrals, and this occurs with the most 

 perfect specimens of cervical ribs ; so that while the upper part of the spine is archaic, the 

 number of praesacrals is diminished, which is thought to be a progressive feature. 



Turning now to rudimentary 1st ribs: in G-22, which is not a perfect case, as the 1st 

 ribs are only small and not rudimentaiy, there is an extra thoracic vertebra ; in A-4, a 

 typical case, there is the same ; in the incomplete specimen 572 there is a record of 6 

 lumbar vertebrae ; Leboucq describes a case with one praesacral too few, and another 

 with one too many. Here we are confronted by the fact that while the upper part of the 

 spine shows an alleged step towards the future, the lower part shows one towards the 

 past. Surely such a series of diametrical contradictions, both in the cases of cervical ribs 

 and of imperfect 1st thoracic ones, is fatal to a theory, to say nothing of the chfficulty of 

 accounting for the fusion of the atlas and occiput on evolutionary grounds, and ignoring 

 the question whether cei'vical ribs, if archaic, are not too archaic to be taken seriously. 



It cannot be denied that it is a very serious criticisin on Rosenberg's theory that a 

 tendency at either end of the spine either to revert to the past or to stretch forward to 

 the future may be associated with a tendency at the other of a chrectly opposite signifi- 

 cance. The question then arises whether there is not some explanation that would 

 account for both. Now in several cases in this series, and there are plenty like them in 

 the literature, we see a tendency sometimes for the whole thorax to move forward by cer- 

 vical ribs associated with absence of the last thoracic ones or with their existence in a 

 rudimentai-y condition. We also see cases in which, when the cervical rib on one side is 

 distinctly larger than its fellow, the last rib on that side is either correspondingly smaller 



