942 THE OSTEOLOGY AND MYOLOGY OF THE DEATH ADDER, 



the spinalis and semispinalis above. The muscle runs forwards 

 and outwards, the superficial fibres of each bundle pass over the 

 vertebrae to be inserted into the lamina of the fourth, the deeper 

 fibres being attached to the laminae of the vertebrae passed over> 

 The tendons of origin of the spinalis run iipwards and inwards 

 over the muscles, and are closely connected with the aponeurosis 

 stretching between the neural spines and the zygapophyses. Each 

 moiety of the multifidus is triangular in outline, the apex being 

 at the spine, the base at the lamina. As the tendons of the 

 spinalis run inwards they cross the side of the triangle nearest to 

 them ; we thus have a number of acute angular spaces formed 

 whose floor is composed of the aponeurosis mentioned above. It 

 is from these spaces that the spinalis dorsi arises in part. 



If we consider this muscle as multifidus, we are met by the 

 difficulty that the fibres run from the mid-line outwards. But 

 the direction of the fibres being the result of function, and there- 

 fore necessarily inconstant in direction, we do not consider that 

 this is a sufficient reason for not regarding the muscle as multifidus. 



The relation of the nerve, running between the muscles and the 

 semispinalis, adds to the idea of its homology with the multifidus. 



In Hydrosaurus the muscle takes the same direction, but each 

 bundle of fibres is in this case arranged around a strong tendon in 

 a pinnate manner, the tendon running from the neural spine 

 outwards to the laminae and zygapophyses. 



As we have shown, the multifidus is attached to the laminae 

 over which it passes, and some of the lowermost fibres conse- 

 quently pass from one lamina to another only. We, therefore, 

 get a series of small muscles which represent the rotatores dorsi. 

 Those are described by D' Alton as "die obere Reihe zwischen den 

 Gelenkfortsatzen ;" and by Hofi"mann as part of the intertrans- 

 versarii. The nerve fibres pierce these muscles. 



Mm. interspinales. 



Mm. inter spinales, Hoffmann, Owen ; Zwischendw^nmuskelriy 

 Hiibner, Meckel, D' Alton. 



