278 
THE GEOLOGIST. 
from the Permian formation to the Chalk inclusive ; their special afSnities 
being chiefly with the Ctenododipterini, the 3cales, 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 Coelacanthini ; but among recent fossils there is one, 
the Polypterus, which very nearly approaches the required standard, and 
is unquestionably allied to the Saurodipterini. These results are then put 
in a tabular form thus : — 
Order GANOIDEI. 
Sub-orders — 
I. Amiadje. 
II. LEPIDOSTEIDiE. 
III. Chossopteetgid.i:. 
Fam. 1. P0LTPTEEI?fI. 
Dorsal fin very long, multifid ; scales rhomboidal. 
Ex. Polypteriis. 
Fam. 2. Saueodipterini. 
Dorsal fins two ; scales rhomboidal, smooth ; fins sub- 
acutely lob ate. 
Ex. Diplopterus, Osteolepis, Meqalichthys. 
Fam. 3. GLYPTODIPTEEI^fl. 
Dorsal fins two ; scales rhomboidal or cycloidal, sculptured ; 
pectoral fins acutely lobate ; dentition dendrodont. 
Sub-Family A, with rhomboidal scales. 
Ex. Glyptolcemus, Glyptoporaus, GyroptycMus. 
Sub-Family B, with cycloidal scales. 
Ex. Solopiychhis, Gh/ptolepis, PlatygnatJius 
[Hkizodus, Dendrodus, Cricodus, Lam- 
nodus]. 
Fam. 4. Ctenodipteeixi. 
Dorsal fins two ; scales cycloidal ; pectorals and ventrals 
acutely lobate ; dentition ctenodont. 
Ex. D'ipterus \_Ce7'atodus i 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. JBlianeroplenron. 
Fam. 6. Ccelacanthini. 
Dorsal fins two, each supported by a single interspinous 
bone ; scales cycloidal ; paired fins obtusely lobate j air- 
bladder ossified. 
Ex. Coelacanthus, Undinay Macropoma. 
IV. Chondeosteid-s;. 
V. ACANTHODID^. 
