770 HUXLEY AND HIS WORK. 



Subordo III. — Crossopterygidte — Continued. 

 Fam. 2. — Satjrodipterini. 



Dorsal fins two ; scales rhomboidal, smootli ; fins subacutely lobate. 

 Diplopterus, Osteolepis, Megalicliihys. 

 Fam. 3. — Glyptodipterixi. 



Dorsal fins two; scales rhomboidal or cycloidal, sculptured; pectoral 

 fins acutely lobate ; dentition dendrodont. 

 Sub-fam. A. with rhomboidal scales. 



Glyptolcemus, Glyptopomus, Gyroptychius. 

 Sub-fam. B. with cycloidal scales. 



Roloptycliius, Glyptolepis, Platygnathus [Bhizodus, Dendrodus, Crico- 

 dus, Lamnodiis~\. 

 Fam. 4.— Ctexododipterixi. 



Dorsal fins two; scales cycloidal; pectorals and ventrals acutely lobate ; 

 dentition ctenodont. 

 Dipterus [Ceratodusf Tristicliopteru8?~]. 

 Fam. 5. — Phaxeropleurixi. 



Dorsal fin single, very long, not subdivided, supported by many inter- 

 spinous bones; scales thin, cycloidal; teeth conical; ventral fins 

 very long, acutely lobate, 

 Phaneropleuron. 

 Fam. 6. — Ccelacaxthixi. 



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

 cycloidal; paired fins obtusely lobate; air bladder ossified. 

 Ccelacanthus, Undina, Maeropoma. 

 Subordo IV. — Chondrosteid^;. 

 Subordo V. — Acaxthodid^e. 



The chief merit in this arrangement is the appreciation of the close- 

 ness of the relations between the extinct fishes of the groups now rec- 

 ognized as Dipnoans and Crossopterygians, and the anticipation, by 

 a kind of intuition, of part of the truth as now recognized. The 

 "suborder Crossopterygidre " of Huxley is really a compound of the 

 subclasses or superorders of Dipnoans and Crossopterygians. The dis- 

 tinctive characters of the two were not recognized, and the author 

 even failed to appreciate the exact relations of the living and extinct 

 Dipnoans, or that, in fact, many of his Crossopterygidse are really 

 Dipnoans. 1 In his Anatomy of the Vertebrates (1871), even he retained 

 his arrangement of the "Gauoidei," which were placed as the fourth 

 order of fishes, and considered the " Dipnoi" after the Teleostei and as 

 the sixth order of fishes. He failed even to find any extinct Dipnoans, 

 and concluded his observations on the group with the statement that 

 "It is a remarkable circumstance that, while the Dipnoi present, in so 

 many respects, a transition between the piscine and the amphibian 

 types of structure, the spinal column and the limbs should be not only 

 piscine, but more nearly related to those of the most ancient Crossop- 

 terygian Ganoids than to those of any other fishes." 2 



'The Polypterini, Saurodipterini, Glyptodipterini, and Ccelacanthini are alone 

 regarded as " Crossopterygii" by recent palichthyologists, the Ctenodipterini and 

 Phaneropleurini being regarded as "Dipnoi." 



2 It may not be out of place for me to remark here that even earlier, in 1861, than 

 the publication of Huxley's paper, I had recognized the lommon characters of the 



