Müller proposed several other not unimportant modifications of the Cuvierian system; and although all cannot be maintained as the most natural arrangements, yet his researches have given us a much more complete knowledge of the organisation of the Teleosteous fishes, and later enquiries have shown that, on the whole, the combinations proposed by him require only some further modification and another definition to render them perfectly natural. Under the name of _Pharyngognathi_ he combined fishes with the lower pharyngeals coalesced into one bone, viz. the Labroids, Chromides, and Scombresoces. The association of the third family with the two former seemed to himself a somewhat arbitrary proceeding; and it had to be abandoned again, when a number of fishes which cannot be separated from the Acanthopterygians, were found to possess the same united pharyngeals. A more natural combination is the union of the Cod-fishes with the Flat-fishes into the order _Anacanthini_. Flat-fishes are in fact nothing but asymmetrical Cod-fishes. Müller separates them from the remaining Malacopterygians by the absence of a connecting duct between the air-bladder and oesophagus. However, it must be admitted that the examination of those fishes, and especially of the young stages, is not complete enough to raise the question beyond every doubt, whether the presence or absence of that duct is an absolutely distinctive character between Anacanths and Malacopterygians. Many of the families established by Cuvier were reexamined and better defined by Müller, as may be seen from the following outline of his system:-- Sub-classis I.--Dipnoi. Ordo I.--Sirenoidei. Fam. 1. Sirenoidei. Sub-classis II.--Teleostei. Ordo I.--Acanthopteri. Fam. 1. Percoidei. „ 2. Cataphracti. „ 3. Sparoidei. „ 4. Sciænoidei. „ 5. Labyrinthiformes. „ 6. Mugiloidei. „ 7. Notacanthini. „ 8. Scomberoidei. „ 9. Squamipennes. „ 10. Taenioidei. „ 11. Gobioidei. „ 12. Blennioidei. „ 13. Pediculati. „ 14. Theutyes. „ 15. Fistulares. Ordo II.--Anacanthini. Sub-ordo I.--Anacanthini sub-brachii. Fam. 1. Gadoidei. „ 2. Pleuronectides. Sub-ordo II.--Anacanthini apodes. Fam. 1. Ophidini. Ordo III.--Pharyngognathi. Sub-ordo I.--Pharyngognathi acanthopterygii. Fam. 1. Labroidei cycloidei. „ 2. Labroidei ctenoidei. „ 3. Chromides. Sub-ordo II.--Pharyngognathi malacopterygii. Fam. 1. Scomberesoces. Ordo IV.--Physostomi. Sub-ordo I.--Physostomi abdominales.