SAUROPTERYGIA. 241 



slender, hollow bones (fig. 92, a), from the German muschel- 

 kalk, were referred by Count Miinster to the class JRejotilia, 

 under the name of Macroscelosaurus, under the impression 

 that they were bones of the limbs. H. Von Meyer subse- 

 quently, in more perfect specimens, observing that each 

 slightly expanded extremity of the long bone was terminated 

 by a symmetrical oval concave articular surface, surmounted 

 by a pair of symmetrical lateral incurved plates, resembling 

 confluent neurapophyses, with articular surfaces, and with 

 their sometimes confluent bases arching over a neural canal 

 (as in figure B, in cut 92), recognized their vertebral character ; 

 and, adopting the determination of their reptilian nature, but 



Kg. 92. 



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



repudiating the idea of their being limb-bones, he discarded 

 Miinster's name, and substituted for it that of Tanystrophceus* 

 indicative of their peculiar proportions as vertebrae. Although 

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

 intervening body is not so. It is sub compressed, usually 

 broader and flatter below than above ; sometimes more flat- 

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

 tically 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 



* From ravvu, to elongate, ffT^apcu, verto. 

 R 



