SAUROPTERYGIA 221 



neurapophyses, with articular surfaces, and with their some- 

 times confluent bases arching over a neural canal (as in figure 

 b, in cut 70), recognized their vertebral character ; and, adopt- 



Fig. 70. 

 a, b, Tanystrophazus (Trias) ; c, Ichthyosaurus. 



ing the determination of their reptilian nature, but repudiating 

 the idea of their being limb-bones, he discarded Miinster's 

 name, and substituted for it that of Tanystropliams? indicative 

 of their peculiar proportions as vertebras. Although the 

 articular ends are for the most part symmetrical, the long- 

 intervening body is not so. It is subcompressed, usually 

 broader and flatter below than above ; sometimes more flat- 

 tened on one side than on the other, giving an irregular, verti- 

 cally oval, or triangular cross section. A low median ridge is 

 not uncommon on the lower surface towards the ends of the 

 vertebra ; and similar less regular ridges project from the 

 sides of the otherwise smooth outer surface. The centrum is 

 excavated by a canal, resembling a medullary one, but more 

 probably filled, in the recent state, as in the long caudal style 

 of the frog, with unossified cartilage. The walls of this cavity 

 are compact, and in thickness about one-sixth of the diameter 

 of the bone. The terminal neural arches support each a low 

 median ridge or rudimental spine, which soon subsides. The 

 trace of neural canal in like manner disappears, or is continued 

 by two distinct slender canals, which traverse for a certain 

 extent the substance of the thicker upper wall of the cavity 

 of the vertebral body. A single large vascular canal opens on 

 the wider surface midway between the two ends of the body. 



* From ravvw, to elongate, arpttyw, verto. 



