224 



ANATOMY OF VERTEBRATES. 



143 



A 



jaw from b to c, upon the tympano-mandibular joints, t. Obser- 

 vation of this action engendered the notion that the upper jaw 

 was moveable, and that this was a peculiarity of the Crocodile ; 

 but it moves only as part of the entire cranium. 



As the muscles of the limbs reach their maximum of number 

 and variety in the Chclonia and saltatory Batrachia, they will be 

 specified in those groups ; and the myology of the trunk will be 

 resumed, as it is seen in the Opkidia. 



In these reptiles, as might be expected from the functions of 

 the spinal column, specialisation of the muscles of the vertebra? 

 and ribs reaches its maximum. The coalescence of the upper or 

 neuromcsial and neurolateral parts of the myocommas into longi- 

 tudinal tracts is more complete and distinct than in the fish-like 



Batrachia, or the Crocodilia ; 

 the primitive distinction or 

 segmentation being pre- 

 served only at the points of 

 attachment. 



In the neuromesial tract, 

 fig. 143, A, those which 

 may be called ( origins ' are 

 in two series, one from the 

 bases of the neural spines, 

 the other by short tendons 

 from the diapophyses : the 

 fleshy fibres from each ori- 

 gin converge and coalesce 

 as they pass forward, and 

 terminate in a lono; slender 



o 



tendon : these tendons are 

 attached to the summits 

 of the neural spines. We 

 have here the characters 

 of semispinalis and spinalis 

 dorsi. The column external 

 to the preceding answers to 

 the lonyissimus dorsi ; it 

 arises by a series of fleshy 

 origins from the transverse 

 processes, and by tendons 

 from the contiguous parts 

 of the ribs ; the fleshy fibres 

 pass forward and outward partly to the fascia covering the 



Muscles of the vertebra and ribs. Python, cxci. 



