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THE EARLY DEVELOPMENT OF AMIA. 413 
The Early Development of Amia, 
By 
Bashford Dean, Ph.D., 
Columbia College, New York. 
With Plates 30—32. 
Ganorps, or more accurately Crossopterygians and Chondro- 
stean Actinopterygians, must be looked upon as, in many ways, 
a transitional and intermediate group. For, on the one hand, 
the evidence is becoming conclusive that the Teleosts are to 
be regarded as its highly differentiated descendants; and, 
on the other hand, its most primitive members have certainly 
the closest ties of kinship with both the early sharks and lung- 
fishes.! 
Amia calva is doubtless, at the present day, the sole 
survivor of the race of Mesozoic Ganoids of which Caturus 
or Megalurus may be taken asa type. It claims, therefore, 
an especial interest as most nearly the ancestral form of some, 
if not all, of the recent Teleosts; for its structures are pecu- 
liarly Teleostean, and its closely kindred forms occurring from 
the Oolite to the Cretaceous provide the actual stepping-stones 
to the Clupeoids. 
But in embryology the Ganoid and the Teleost still stand 
widely separate, and there has even been a tendency to look 
1 The writer refers to the structural nearnesses of the early Crossoptery- 
gians (e.g. Gyroptychiids), Phaneropleurid Dipnoans, and Pleuracanth 
sharks. He also notes that decidedly shark-like features are now found to 
be present in the early development of the sturgeon, and especially of the 
gar-pike. 
VoL. 38, PART 4,—NEW SER. FE 
