355 



from the ethmoid region of the skull contemporaneously with the for- 

 mation of bone. It is the rootpiece of the maxillary tentacle and is 

 worked in Siluroids by muscles, never in them entering into continuity 

 with the pterygoid elements of the upper jaw. The maxillary bone 

 arises as a small dermal bone at the base of the tentacle x ). 



Nasal tentacle 



Pmx. piece 



Prepal. 



Mx. tent. - " 



Cor. tent. 



Mental tent, 



R. ophth. prof. 



Ethmoid. Region of Skull 

 Trig. II 



ü!/w#. H y° id 



iiinil/niiiilillliii" "iii'iu,,.,,, 



R. ment. ' ', 



R. submand. Submand. tent. 

 Fig. 4. Tentacles and sensory Nerves of Siluroids Ideal diagram. 



The third tentacle is the coronoid, most typically shown in Tricho- 

 mycterus where it is very long. Its base passes continuously into a 

 large procartilaginous rootpiece which is firmly attached to the car- 

 tilaginous coronoid process of the lower jaw (whence its name) thus 

 strongly recalling the relations in Myxine. This rootpiece which is 

 very large in Siluroids (except Callichthys) and occurs in many 

 Teleostei seems to have curiously escaped notice. Müller mentions 

 it briefly for Sciaena. It has no muscles in connection with it. The 

 nerve supply to the above two tentacles is from the second division 



1) Adnasal, Mc Mueeich, of. Ridee, Dev. of Osseous Fishes, U.S. 

 Fish Commision 1885. 



