NUMERICAL VARIATION IN THE Hr:MAN SPINE. 249 



last costal elements are in G 19 and 636, though occurring in the former at the 19th, and 

 in the latter at the 20th vertebra. 



Group B. 



This group, like the preceding, has the normal number of praesacral vertebrae, but 

 there is some irregularity in the costal element at the jiuiction of the neck and back. 

 This might consist either in cervical ribs or in a want of development of the 1st thoracic 

 rib. In point of fact the only complete spine with the latter anomaly has to be put in 

 another group. The same is true of several cases of cervical ribs. 



1. Cat. 9379-44. 



• Adult. C. 7, T. 12, L. 5, S. 5, C. imperfect. 



A pail- of small cervical ril)s, the right one fused, the left free. Length of right rib 

 along anterior cur\e 2.7 cm. It ends free in a sharp point al)Out 1 cm. beyond the trans- 

 verse process. The left one is longer (4. cm.) and much more evidently a rili. with head, 

 neck, and tubercle. All these parts are minute. It also ends free in a sharp pdint 

 directed forward. On the left the so-called costal element of tlie 7th vertebra is present 

 behind the rib, with the usual transverse foramen.' The 1st thoracic ribs are not quite 

 typical, the left one, especially, being uncommonly long and narrow. Though inserted 

 as a 1st rib, it resembles a 2d. The lltli ribs measure 17.2 cm. on the right, and 16.7 

 cm. on tlic left. The 12th pair is rather small: 7.8 cm. on the right, and 7. cm. on 

 the left. Tile change in the articular process occurs normally. The transver.se process 

 of the 4th lumbar is that of a penultimate on the right, but not on the left. 



This spine is in most respects, and as a whole, very normal. There is, how^ever, a 

 greater peculiarity tlian the presence of cer\'ical ribs. It is the concomitant change in 

 the 1st thoracic ribs and the lack of development of the 12th pair, hinting at a ten- 

 dency of the thorax to move upward. 



A-3(). Cat. 9379-31. 



Black, male, aet. 22. C. 7. T. 12, L. 5, S. 5, (C. 4 ?) . 



There is a small cervical ril) (jn the left, con.sisting of a minute head, tubercle, neck 

 and shaft, ending free in a point. The length, following the curve, is 2.6 cm. The right 

 costal element of the same vertebra is wanting, probably lost, ftjr there is tlie faintest 



' For the explanation of this condition vide Leboucq ('96 -'98). 



