341 



on the 7th vertebra, and that there is a peculiar form of bicipital 

 rib which is seen only in the thorax. On the other hand, while several 

 instances of defective 1st thoracic rib are very much alike, it is im- 

 possible to distinguish them with certainty from cervical ribs. 



H-3 is a very interesting and perplexing case. If the ribs of the 

 7th vertebra are to be considered cervical, we probably have here 

 another instance of a cervical rib of the kind found in 202, though 

 in the absence of the sternum it cannot be certain. I incline, however, 

 to consider them as thoracics placed too high, one of them being 

 rudimentary. Lane ('85) reports an interesting case of the converse 

 condition, in which the 8th vertebra bore on one side a rib which he 

 considers cervical, that from the 9th being practically a normal 1st 

 thoracic one. Leboucq reports two cases in which the 8th vertebra 

 bears rudimentary ribs quite like cervical ones. These cases certainly 

 point strongly to the likelihood that vertebrae of different numbers 

 at this end of the thorax also may assume similar features. They 

 show, moreover, how unsatisfactory the terms "cervical" and "thoracic" 

 are in this connection. 



Bicipital ribs sometimes occur and may be due to the fusion 

 of a cervical rib with a 1st thoracic, or to the fusion of a 1st thoracic 

 with the 2d. An instance of each is presented in 649 and in the 

 incomplete specimen C-1, respectively. In the former the cervical rib 

 soon joins the other, which presents no marked enlargement of its 

 shaft, but the latter specimen shows a great broadening. Indeed it 

 is evident that there are two ribs united even before it branches at 

 jithe front into a normal 1st and 2d. Several instances of this latter 

 ticondition have been described, but for the most part without con- 

 clusive data as to the number of the ribs. They have, however, a 

 general family likeness and, moreover, one point of resemblance which 

 ijperhaps has not been noted. It is the nearness of the two heads to 

 one another. In this specimen they both rest on the 8the vertebra. 

 This last point is very striking in all illustrations. While I believe 

 that these two types are distinct, and represent what is commonly 

 5een at different levels of the spine, I would not undertake to say 

 :hat either may not be found some time at the level of the other. 



Q this series there is one case (208) of the fusion of the three upper 



horacic ribs. 



Fusion of Atlas and Occiput. There is no reason why this 



ccurrence should not have the same weight iu the numerical variations 



f the spine as fusion at other points. There are several specimens 



