pit lines 



.occipital line 



supraorbital line 



infraorbital line 



oral division' 



lateral line 



pectoral fin 



mandibular and preopercular divisions ventral sensory lir 



hyoid arch line 



external 

 nasal opening 



nfraorbital line 



oral division 

 infraorbital line pores 



supraorbital line indicated by canal pores 



mandibular division 



temporal division 



pectoral fin 



lateral line 



ventral sensory line 



Figure 13-32. Sensory canal grooves and tubes on the head of Profopterus. A, lateral view; B, 

 dorsal view; C, ventral view. 



supraorbital line 



infraorbital line 



hyoid ari 

 mandibular arch line 



•^ I anterior pit line 



temporal ^ \ 



postorbi 



supratemporal organ 

 posterior pit line 



nfraorbital line | ---^^opercular pl( 



mandibular arch line mandi 



lorsal line X 

 lateral line X 

 suprabranchial line 

 hyoid arch line 

 opercular placode 



8.6 mm 



B 



10 mm 



10.6 mm 



1 1.5 mm 



Figure 13-33. Four stages in the development of the sensory-line system in Neoceratodus. (After 

 Pehrson, 1949) 



SENSORY ORGANS • 417 



