270 



SUBPHYIUM VERTEBRATA: 



pectoral spine 

 ACANTHODES 



branchial openings 



pectoral fin 



spines 

 CLIMATIUS 



PLEURACANTHUS 



Figure 16.4 Restorations of some fossil shark-like fishes. Acanihodes and Cl'imatus were Placo- 

 dermi; C/adose/ache and P/euroconfhus were Chondrichthyes. (From Malcolm Jollie, Chordate 

 Morphology, Reinhold Publishing Corp., New York, 1962.) 



ORDER MYXINOIDEA (Hagfishes or Slime Eels) 



Diagnosis: mouth essentially terminal, ringed by 

 four pairs of tentacles, without a sucking funnel, eyes 

 covered by skin; 10 to 14 pairs of gill pouches open- 

 ing some distance behind each covered eye; dorsal fin 

 undivided; hermaphroditic, but with only one kind of 



sex gland mature at a time, eggs large, no larval 

 stage; strictly marine. 



The Cyclostomata, literally "round mouths," are 

 jawless fishes that now are represented by two orders, 

 the lampreys and the hagfishes. The lampreys are 

 parasitic and free-living; the. hagfishes are either fish 



CHEIROLEPIS 



.dorsal fin 



STEGOTRACHELUS 



PTERONISCULUS 



Figure 1 6.5 Restorations of some fossil, primitive Actinopterygii, Superorder Chondrostei. 

 {From Malcolm Jollie, Chordote Morphology, Reinhold Publishing Corp., New York, 1962.) 



