532 MULLER ON THE STRUCTURE OF THE GANOIDS, 
If we remove these four sections of fishes, two others still 
remain having opercula and free gills, the Ganoids and the true 
spinal fishes, which, independently of all other differences, sepa- 
rate at once by their cardiac valves. I call all true vertebrate 
fishes having two arterial valves Teleostei, i. e. perfect osseous 
fishes. We thus have six subclasses based on solid and certain 
characters, such as Cuvier desired but failed to obtain. 
1. Teleostet, Mill. 2. Dipnoi, Mill. 3. Ganoidei, Agass., 
Mill. 4. Hlasmobranchii, Bonap. seu Selachii. 5. Marsipobran- 
chii, Bonap. or Cyclostomi. 6. Leptocardii, Mill. 
The Ganoids and Selachii I place in the centre; the Ganoids 
form on the one side the transition to the Teleostet and Dipnoi, 
the Selachii on the other to the Cyclostomi and Leptocardii. 
The Teleostei, or true vertebrate fishes, I divide into six orders :— 
1. Acanthopteri, Mull. 4. Physostomi, Mill. 
2. Anacanthini, Mill. 5. Plectognathi, Cuv. 
3. Pharyngognathi, Mill. 6. Lophobranchii, Cuv. 
By Acanthopteri I mean those only among Cuvier’s spiny- 
finned fish which have double hyoid bones, as I remove the 
Labroidei and those related to them. In the majority the ven- 
tral fins are near the pectoral fins. Their swimming-bladder, 
when present, is always without an air-tube. The families are 
as follows :— 
Percoidei, Cuv., Cataphracti, Cuv., Sparoidei (including the 
Menides), Scienoidet, Cuv., Labyrinthici, Cuv., Mugiloidei, Cuv., 
Notacanthini, Mill.(Notacanthus, Rhynchobdella, Mastacemblus), 
Scomberoidei, Cuv., Squamipennes, Cuv., Tenioidei, Cuv., Go- 
bioidei, Miill. (including the Cyclopteri) *, Blennioidei, Pediculati, 
Cuv., Theutyes, Cuv., Fistulares, Cuv. 
The family of the Notacanthini includes such Acanthopteri, 
with abdominal or without ventral fins, which have many dorsal 
spines independently of a dorsal fin, and the clavicle of which, 
instead of being suspended from the head, is attached to the 
vertebral column, as in the Eels. The same exists in Notacan- 
thus as well as in Mastacemblus. It remains to be shown whe- 
ther Tetragonurus belongs to this place. 
The Anacanthini are fishes which agree in their internal struc- 
ture with the Acanthopteri; their swimming-bladder, when 
present, has no air-duct, they have also soft rays only. Their 
* See the dbhandlung tiber die Natiirlichen Familien der Fische, Wiegmann’s 
Archiv, ix, 1, p. 295. 
