4. Ventral fins abdominal, inserted a considerable distance behind the 



pectorals 5 



Ventral fins thoracic (in close proximity to the pectoral fins but be- 

 hind) or jugular (ventral fins anterior to pectoral fins) 14 



5. Dorsal fin preceded by free dorsal spines 



Sticklebacks 

 Gasterosteidae 

 p. 51 



Dorsal fin not preceded by free dorsal spines 6 



6. Adipose fin behind 7 



No adipose fin present 10 



7. No scales; barbels on headj single stout spine in dorsal and pectoral 

 fins J adipose fin present 



Brown Bullhead 

 Ameiuridae 



p. 39 



Scales present; barbels absent; pectoral fins without spines 



7 



8 



