183 
of Lepidosteus embryos, originally described and figured by A. Acassız!), 
are also found in Amia embryos, but less developed than in Lepi- 
dosteus. 
In other respects the embryos are almost identical. Recently Dr. 
TRAQUAIR informed me that his palaeontological studies had led him 
to the same result. 
So that now the united evidences of comparative anatomy, embryo- 
logy and palaeontology combine to place Amia among the Lepidosteini, 
and thus to destroy one of the divisions of the Ganoidei. 
It is an open question whether we shall not have to unite the 
whole five families of the Ganoidei much more closely than hitherto, 
and I firmly believe that the so-called Holostean forms are the more 
ancient of the two divisions. 
For instance, the differences between Acipenser and Lepidosteus, 
in points of both comparative anatomy and development, are reasonably 
explicable as due to degeneration in Acipenser. The absence of the 
larval suckers, the state of the skeleton, the restriction of teeth to the 
arva, and the sucking mouth of Acipenser, are all things which point 
to degeneration, and to degeneration from the Lepidosteoid type, as 
exemplified by Amaia. 
Polypterus, too, is allied to the Lepidosteini; many points of 
comparative anatomy prove this. 
As Calamoichthys is related to Polypterus, it must share the fate 
of Polypterus. 
Spatularia or Polyodon and Scapirhynchus will probably follow 
Acipenser. 
To the present division less importance should be attached than 
hitherto. 
It would carry us too far to discuss now the views of various 
distinguished morphologists on the grouping of the Ichthyopsida. 
On one or two points I wish, none the less, to quote and criticise a 
very great authority. 
In the English edition of his „ComparativeAnatomy“ Prof. Gr- 
GENBAUR says”): „I regard each of these divisions of the Ganoidei 
(Sturiones, Polypterini, Lepidosteini, Amiadini) as highly independent. 
1) Acassiz, A., The development of Lepidosteus. Part I. Proc, 
Amer. Acad. Arts and Sciences, Vol. XIV, 1879, 
2) p. 409. 
