OEDEES OF FISHES. 141 



Fam. 6. — Ccelacanthini. 



Dorsal fins two, each supported by a single interspinous bone; 

 scales cycloidal ; paired fins obtusely lobate ; air - bladder 

 ossified. Ccelacanthus, Undina, Macwpoma. 



As regards the above arrangement of the Crosso'pUrygidce, 

 the chief change which has been effected by recent researches 

 relates to the group of the Ctenodipterini. Thus, it has been 

 shown that Gcratodus and Dipterus are not only closely allied 

 to one another, but that the former is related to Zepidosiren 

 by characters which appear to have an ordinal value. Tris- 

 ticliopterus, on the other hand, has been shown by Traquair 

 to belong to the cycliferous division of the Glyptodipterini. 

 The result of this is that the group of the Ctenodipterini 

 must be removed from association with the Crossopterygious 

 Ganoids, and must stand in future as a section of the order 

 Dipnoi. The only alternative step is to reduce the Dipnoi 

 from the rank of an order to that of a mere section of the 

 Ganoidei. The present condition of our knowledge of this 

 subject will probably be best expressed if we subjoin here 

 the following table, showing the classification of the Grossop- 

 terygidce proposed by Dr Traquair (Trans. Eoy. Soc. Edin., 

 vol. xxvii.) : — 



Section I. — Caudal dipliycercal, but witli shortened body-axis. Dor- 

 sal fin multifid, pectorals obtusely lobate, scales rhomboidal. 



Fam. 1.— Polypteridse {Polyptenis, Calamoichthys). 



Section II. — Caudal with elongated attenuated body-axis, heterocercal 

 or dipliycercal. 



A. Pectorals obtusely lobate, tail diphycercal, dorsal fins tAvo, 



scales cycloidal, air-bladder ossified. 



Fam. 2. — CcElacanthidse {Gcelaccmthus, Macropoma, 

 Holophagus). 



B. Pectorals sub-acutely lobate, dorsal fins two, tail heterocercal or 



diphycercal. 



a. Scales rhomboidal. 



Fam. 3. — Ehombodipteridse. 

 * Scales sculptured. 



Sub-fam.— Glyptolsemini {Qlyptolcemus, Glt/p- 

 topomus). 

 ** Scales smooth. 



