Correction

		Mesacanthidae	Cheiracanthidae	Howittacanthidae	Acanthodidae
Intermediate spines		1 pair	no	no	no
Spines insertion in the musculature		superficial	deep	deep	deep
Pelvic or ventral spines	Presence	paired	paired	paired	unpaired or none
	Position	around middle or closer to anal spine	different	close to anal spine	close to pectoral spine or around middle
	Length	short or medium	medium or long	medium	short or none
Gill chamber		short and deep	short and deep	short	elongated
Branchiostegals		strong	strong	weak	weak
Dorsolateral sensory lines		absent	present	present	absent
Scales		smooth	smooth or ornamented	smooth	smooth
Mandibular bone		present	present or absent	present	present
Acanthodes-like jaws (LONG 1986)		absent	absent	present	present

The families of the order Acanthodiformes and comparison of their main features.