THE DERMAL MUSCLES. 9 



8. The cleido-tracheales.- -These muscles are highly 

 developed in the Kaven, and seem to take the place of 

 the sterno-maxillaris of Owen. 1 Each arises from a 



two-thirds of the neck, besides being acted upon by the constrictor 

 colli, is braced down by a thin stratum of oblique and somewhat 

 scattered fibres, dermo-transversalis, which take their origin by 

 fascise attached to the inferior transverse processes of the sixth to 

 the twelfth cervical vertebrae inclusive ; the fibres pass obliquely 

 upward and backward, and are inserted by a thin fascia into the 

 median line of the skin covering the back of the neck " (Anat. of 

 Verts., vol. ii., p. 111). 



The dermal system of muscles is highly developed in the Apteryx, 

 and this may account for the absence of the sterno-cervicalis in such 

 a form as the Raven, or its occurrence in a very rudimentary con- 

 dition, which I failed to discover. The same author says : " The 

 sterno-cervicalis arises fleshy from the posterior incurved angular 

 process of the sternum, from the ensiform prolongation and middle 

 line of the outer and posterior surface of the same bone. The 

 fibres pass forward, and, diverging in gently-curved lines, ascend 

 upon the sides of the broad base of the neck, and are inserted by a 

 thin but strong fascia into the median line of the dorsal integument. 

 This muscle is a line in thickness at its origin, but becomes thinner 

 as it expands ; the anterior part is covered by the posterior fibres of 

 the constrictor colli" (loc. cit., p. 110). 



Since writing this footnote I ascertain that the sterno-cervicalis 

 of Owen is considered by Gadow to represent the deep layer of 

 his mi. cucullaris (Bronn's Klassen des Tkier Reichs, vi. Band, 

 p. 214). 



1 " The sterno-maxillaris [in the A'pUrix\ appears at first view to 

 be the anterior continuation of the preceding [sterno-cervicalis], but 

 is sufficiently distinct to merit a separate description and name. It 

 arises fleshy from the anterior part of the middle line of the sternum, 

 passes directly forward along the under or anterior part of the 

 neck, expanding as it proceeds, and gradually separates into two 

 thin symmetrical fasciculi, which are insensibly lost in the integu- 

 ment covering the throat and angle of the jaw. It adheres pretty 

 closely to the central surface of the constrictor colli, along which it 

 passes to its insertion. It retracts the fore-part of the skin of the 

 neck, and also the head. Each lateral portion acting alone would 

 incline the head to its own side ; the whole muscle in action would 



