The oral cirri of Siluroids and the origin of the head Vertebrates. 393 



dowDWiirils in front of the coronoid piece, then tlividing into two twigs 

 which sup])ly respectively the anterior faces of the maxillary and 

 coronoid tentacles. The third middle branch runs down, internal to the 

 coronoid piece, and supplies the posterior face of the maxillary tentacle. 



The lianms niandibularis gives off a Ramus coronoideus (R. cor.) 

 which runs forward , outside and parallel to the R. maxillaris , and 

 turning down, proceeds to the posterior face of the coronoid tentacle. 



The Rainus mamlibularis , passing downwards, runs internal to 

 the coronoid process and divides into mental and submandibular nerves, 

 besides giving off motor libres The Ramus submandibularis (R.suhm.) 

 turns backwards, outside the coronoid process, and supplies the skin 

 below the Meckeliau cartilage, while the R. mentalis (R.ment.) is 

 continued forwards to the front of the dentary region. 



Sensory Tentacular Nerves of Callichtliys (Fig. 10). 



The main stem of the Trigeminus passes below the eye, giving 

 off behind that organ a palatine branch, which divides into several 

 small twigs supplying the roof of the mouth. 



Below the centre of the eye the main stem divides into two 

 branches, an upper and lower. The upper gives oft' shortly a Ramus 

 premaxilhiris (R.pmx.) and, as the Ramus maxillaris (R.mx.)^ runs 

 forward along with the R. premaxillaris in a space between the ad- 

 ductor mandibulae and adductor arcus palatini muscles. The Ramus 

 premaxillaris gives off" small branches to the skin in the antorbital 

 region and passes forward, lying near the skin outside the prepalatine 

 piece, dividing into small twigs in the premaxillary region. 



The Ramus maxillaris, running forward , divides into 1) a small 

 branch which passes outwards and downwards and along the posterior 

 face of the coronoid tentacle, 2) a large branch which runs down 

 outside the maxillary tentacle and divides into four twigs, two of 

 which supply the anterior and lateral face of the coronoid tentacle, 

 and the other two the posterior face of the maxillary tentacle, 3) a 

 branch which divides above the velar support, some twigs supplying 

 the lateral part of the anterior region of the roof of the mouth, the 

 remaining branch passing down inside the maxillary tentacle to supply 

 its anterior face. 



The Ramus mandibularis (R.md.) gives off a Ramus coronoideus 

 (R.cor.), which is small and runs above and outside the adductor 

 mandibulae muscle, turning down to supply the posterior face of the 

 coronoid tentacle. 



