390 H. B. POLLARD, 



Below and in front of the prepalatine cartilage is seen the three- 

 rayed, procartilaginous premaxillary piece, forming the tip of the 

 snout (Pmx.p.). 



The maxillary tentacle {31x. t.) is attached to the prepalatine car- 

 tilage through the intermediation of the maxillary bone. The tentacle 

 itself passes sharply downwards and backwards, below the coronoid 

 tentacle. Behind the maxilla lie the paired, external tentacle-like 

 supports of the velum (1. v. s.). 



Only the mentomeckelian portion of the lower jaw (m. Mck.) is 

 seen in the model. A coronoid process is not developed, and the 

 coronoid piece is only represented by a procartilaginous rudiment, not 

 shown in the model. The coronoid tentacle (Cor.t.) proceeds backwards, 

 almost parallel with the mentomeckelian cartilage , and it is fused 

 with the distal portion of the mental tentacle {Ment. t.). The mental 

 tentacles, which have a beautifully curved form , are fused with one 

 another at their bases in the middle line, below the premaxillary piece. 

 The junction is in front of, and slightly below the symphysis of the 

 dentary bones. 



The distal fusion of the mental and coronoid tentacles deserves 

 especial attention. 



Sensory Tentacular Nerves of Auchenaspis (Fig. 8). 



The trigeminal nerve passes out from the skull, along with the 

 Facial, in front of and below the hyomandibular articulation, thence 

 passing downwards and forwards below and somewhat internal to the 

 eye, which in Siluroids is small. Just below the optic nerve it divides 

 into two great branches, the upper and internal shortly dividing into 

 palatine (B.pal.) and maxillary branches. The lower branch slightly 

 further forwards divides into Ramus coronoideus and Ramus mandi- 

 bularis. 



The palatine branch, after separating from the maxillary, passes 

 inwards through an anterior portion of the adductor arcus palatini 

 muscle, that part which stretches from the skull wall in the anterior 

 orbital region to the posterior end of the prepalatine piece, and which 

 moves the maxillo-coronoid barbule. The motor nerves to this muscle 

 run along with the palatine nerve. Reaching the skull wall the i)re- 

 palatine nerve passes downwards and forwards, beneath and infernal 

 to the preorbital process, lying in fact beneath the lower wall of the 

 passage of the olfactory nerves. Here it runs alongside the edge of 

 the vomer and, reappearing in front of the postorbital process, pro- 



