48 



ANATOMY OF VERTEBRATES. 



BkeU^toii of tlic Monopdmo 

 or rrotonopsia 



half of the transverse process : they are wanting 

 in the twenty-one following vertebras, and re- 

 appear, well developed, in the thirty-first, where 

 they form with cartilaginous ha3inapophyses, a 

 pelvic arch. In the Menopome, fig. 4.3, the 

 second to the nineteenth vertebras support short 

 straight plevirapophyses, articulated to the ends 

 of transverse processes formed by par- and di- 

 apophyses, which intercept by their terminal 

 confluence an arterial canal. These processes, 

 t, are enlarged in the twentieth vertebra, s, and a 

 second rib-like piece, 62, the homotype of the 

 second part of the scapula in fishes, is articulated 

 to the short and thick rudimental rib, pi; the 

 inferior or ha3mal arch 63, 64, being cartilaginous. 

 The segment thus completed by tlie htemal arch, 

 represents a so-called ' sacral ' vertebra : the 

 second division of its rib answers to the ' ilium,' 

 6-2, and the hajmal cartilage to the ' ischium,' or 

 ' pubis.' Transverse processes t, progressively 

 decreasing in length are developed from the six 

 succeeding vertebras. Bony pleurapo})hyses pi, 

 are attached to the first of these, and cartila- 

 ginous rudiments of the same element to the 

 three following. Hasmal arches are anchvlosed 

 to the under part of the centrum of the second 

 to the twelfth caudal vertel^ra inclusive, and 

 these become more compressed to the cud of the 

 tail, for the support of a vertical fin. The ueiu-al 

 arches are broad, depressed, anchvlosed to the 

 centrum : they are complete to the fourteenth 

 caudal vertebra. The body of the atlas pre- 

 sents an odontoid process between the two arti- 

 cular surfaces for the occipital condvles ; it is 

 deeply cupped behind, as are the succeeding 

 vertebras at both ends. This vertebra has neither 

 di- nor pleur-apoiihyses. 



The skeleton of the Newt ( Triton) resembles 

 that of the jNIenopome iu its general characters; the 

 neural and hannal s])ines are uiore produced in the 

 long tail, supporting there the chief swimming 

 organ of this aquatic batrachian. In one kind 

 the ribs arc more developed, occasioning the sub- 



