REPORT ON THE SPHENISCID^. 61 



The anterior fibres of this accessory muscle are in part continuous with the orio-in of 

 the trachelo-mastoid. 



Action. — The longus colli is the principal flexor of the neck. 



Relations. — This muscle is separated from that of the opposite side by the two 

 common carotid arteries. 



Nerve supply. — Branches from the anterior divisions of the cervical nerves. 



1 0. Longus colli externus. 



Attachments. — The muscle which I have thus named arises, in common with the preced- 

 ing, from the hyjiapophyses of the anterior dorsal vertebrae. It is separated by a cellu- 

 lar interval from the longus colli, to the outer side of which it lies. The muscular fibres 

 pass forwards and outwards, and, unlike those of the longus colli, do not terminate on 

 separate tendons, but are inserted directly into the transverse processes of the lower four 

 or five cervical vertebrae, where they are inseparably united with the inter-transverse 

 muscles. 



Action. — This muscle co-operates with the longus colli in flexing the neck. 



Relations. — To its inner side is the origin of the longus colli. The large cords of 

 the brachial plexus pass outwards behind it. 



Nerve supply. — Branches from the anterior divisions of the lower cervical nerves. 



(c) Muscles inserted into the Skull. 

 1. Biventer cervicis. 



Diinner Halsmunkel, Merrern. 



Di;r ZwdhducMge Nackenmusk.eJ, "Wiedemann, p. 75. 



Der Zweihduc.hige Nackenmiiskel, Tiedemann, p. 282, Xo. 1. 



Digastrtque du cou, Cuvier, vol. i. p. 237. 



Digastrique. dti cou, Meckel, vol. vi. p. 9, No. 1 . 



Longus colli posticus (part of), Owen, p. 27. 



Bioenter cervicis, Selenka, vol. vi. p. 95, No. 5. 



Long poderieur du cou (faisceau occipital), Gervais au J Alix, p. 1 4. 



Attachments. — This muscle, as observed by Meckel, is developed to a greater extent in 

 the Penguins than in other birds. It consists of a narrow fleshy liand, without any trace of 

 tendinous intersection, which arises from the anterior border of the ihac bone as well as 

 from the spinous process of the second last dorsal vertebra, by means of a flattened tendon. 

 It passes forwards to the occipital bone, where it is inserted into the upper end of the deep 

 groove which separates the most prominent part of that bone from the transverse occipi- 

 tal crest. 



