39 
striking that when their place among fishes was conceded 
they ranked as a separate order (Dipnoi of Miiller)*. 
Attempts were made to connect them with other orders of 
Fishes with various success. Some systematists were per- 
plexed by the affinities of Lepidosiren with several types of 
piscine structure, as well as with the higher class of Am- 
phibia. Professor Owen appears to have seen fully their 
relationship to the Ganoids. The following sagacious and 
comprehensive sentence illustrates his views better than any 
part of his systematic arrangement. 
" It is extremely interesting to find the Ganoid Folypterus, 
which of all osseous fishes most closely resemble3 the Lepi- 
dosiren in its spiral intestinal valve, in the bipartition of the 
long air-bladder, the origin of the arteries of that part, 
and the place and laryngeal mode of communication of the 
short and wide air-duct or windpipe, also presenting the 
closest agreement with the Lepidosiren in the important 
character of the form of the brain."t 
Not only was the general affinity of the Dipnoi to Ganoidei 
thus clearly anticipated, but not unsuccessful attempts were 
made to indicate their nearest allies in that order. In 1839 
Professor OwenJ described the teeth of Frotopterus as re- 
sembling ^' iu their paucity, relative size, and mode of fixation 
to the maxillee, those of the Chimcera and some of the extinct 
cartilaginous fishes, as Cochliodus and Ceratodtts.'^ In 1861 
Professor Huxley, § while discussing the classification of 
Devonian fishes, was led to notice the resemblance between 
the fins of the Crossopterygian Ganoids and those of 
Lepidosiren, One passage of considerable historical interest 
is here cited. 
* Abhandlungen der Akademie der "Wissenschaften zu Berlin, 1844. 
t Comp. Anatomy of Vertebrates, I, 499. 
t Linnean Transactions, vol. XVIII, pt. 2. 
§ Decades of the Geological Survey, X, p. 26. 
