278 



THE GEOLOGIST. 



from the Permian formation to the Chalk inclusive ; their special affinities 

 bein^ chiefly with the Ctenododipterini, the ?cales, the arrangement of 

 the teeth, and the form of the lower jaw presenting many curious 

 analogies. The Glyptodipterine family contains, as we have seen, both 

 cycliferous and rhombiferous genera ; and following out the alliances of 

 the former sub-family, the cycliferous Ctenododipterini and Coelacanthini 

 have been included in the same larger or sub-ordinal group with the 

 Glyptodipterini. On the other hand, tracing out the congeners of the 

 rhombiferous sub-families, we have arrived at the Saurodipterini ; and the 

 question then remains, what other rhombiferous Ganoids naturally arrange 

 themselves at this end of the series ? So far as the Professor is aware, 

 there is no other fossil rhombiferous Ganoid which comes within the scope 

 of the sum of characters common to the Saurodipterini, Glyptodipterini, 

 Ctenododipterini, and Coeiacanthiui ; but among recent fossils there is one, 

 the Polypterus, which very nearly aj^proaches the required standard, and 

 is unquestionably allied to the Saurodipterini. These results are then put 

 in a tabular form thus : — 



Order GANOIDEL 



Sub-orders — 

 I. Amiadje. 



II. LEPIDOSTEIDiE. 



III. Ceossopterygid^. 



Fam. 1. POLYPTERINI. 



Dorsal fin very long, multifid ; scales rhomboidal. 

 Ex. Tolyjpierus. 

 Fam. 2. Saurodipterini. 



Dorsal fins two ; scales rhomboidal, smooth ; fins sub- 

 acutely lobate. 



Ex. Di/plopterus, Osteole-pis, Meqalichthys. 

 Fam. 3. Glyptodipterini. 



Dorsal fins two ; scales rhomboidal or cycloidal, sculptured ; 

 pectoral fins acutely lobate ; dentition dendrodont. 

 Sub-Family A, with rhomboidal scales. 



Ex. Glyptolcemus, G-lyptopomus, Gryropty chins. 

 Sub-Family B, with cycloidal scales. 



Ex. Holopiy chilis, Glyptolepis, Platygnathus 

 {^Rhizodus, Dendrodus, Cricodus, Lam- 

 nodus']. 

 Fam. 4. Ctenodipterini. 



Dorsal fins two ; scales cycloidal ; pectorals and ventrals 

 acutely lobate ; dentition ctenodont. 



Ex. Dipterus [Ceratodus ? Tristichopterus ?] 

 Fam. 5. Phaneropleueini. 



Dorsal fin single, very long, not subdivided, supported by 

 many interspinous bones ; scales thin, cycloidal ; teeth 

 conical ; ventral fins very long, acutely lobate. 

 Ex. Plianeropleuro)!. 

 Fam. 6. Ccelacanthini. 



Dorsal fins two, each supported b}^ a single interspinous 

 bono; scales cycloidal; paired fins obtusely lobate ; air- 

 bladder ossified. 



Ex. Ca^lacanthus, Undina, Mao'upoma. 



IV. ClIONDROSTEIDiE. 

 V. ACANTHODID^:. 



