42 THE STRUCTURE OF MAN 



indicated by the detailed characters of the transverse processes 

 (Fig. 26, 6). [In the Platypus (Ornithorkynchus') reduced 

 cervical ribs remain for life distinct on six of the seven neck 

 vertebrae, being absent from the atlas only, and one or more 

 cervical ribs may occasionally retain their independence among 

 the quadrupedal Mammals generally. 1 ] 



r.th.l'. 



FIG. 27. A, PORTION OF THE THORACIC SKELETON OF AN ADULT FEMALE 



POSSESSED OF A FAIR OF FREE CERVICAL RlBS. 



The twelve normal pairs of thoracic ribs were present. Length of the right cervical rib 

 3-5 cm., of the left 6-7 cm. r.c.vii.', vertebral end of the cervical rib ; r.c.vii." , 

 sternal end of the same, fused with the manubrium sterni (the vertebral and sternal 

 ends being in life connected by a ligamentous band, not indicated in the figure), 

 r.th., first and second sternal ribs. 



B, EXAMPLE OF THE REDUCTION OF THE FIRST PAIR OF THORACIC 



RIBS (AN ADULT MALE). 



There were twelve pairs of free ribs present, the first pair being reduced both in 

 length and calibre. The left of these was 9, the right 8, cm. long, r.th.i.' ', vertebral 

 end of the first rib ; r.th.i.", its sternal end, synostotically imited with the 

 manubrium sterni (st.) ; r.L, fibrous band, formed by retrogression of the missing 

 portion of the rib. 



In both figures, I, II denote the first and second thoracic vertebrae, VI, VII the two last 

 cervical vertebrae. (Adapted from Leboucq.) 



The greatest development of the seventh cervical rib would 

 naturally be that of uninterrupted extension round the neck. 

 Such an extraordinary condition has only apparently been once 

 observed (by P. Albrecht). Cases in which the rib in question 

 unites with the first thoracic rib by its cartilaginous extremity, 

 before reaching the manubrium, are far more frequent. Some- 

 times only the sternal and vertebral ends are found (in either 

 a bony or cartilaginous state), the intermediate part being 

 represented by a fibrous band. In spite of the reduced con- 



1 [Mivart has figured and described (for example) what appear to be practically 

 stages in the redevelopment of the last cervical rib on opposite sides of the same 

 vertebra of a Binturong (Arctictis], Proc. Zool. Soc., Lond., 1882, p. 461.] 



