184 
They represent the last shoots of a very divergent series of forms, of 
which that of the Polypterini has many points of relationship to the 
Dipnoi; the Amiadae, on the other hand, are the nearest allies of the 
Teleostei (Clupeidae). 
It would perhaps be best to separate them completely from the 
Ganoidei. The Sturiones show the greatest resemblance to the Se- 
lachii.“ 
There is scarcely one of these statements with which I can ex- 
press agreement. The whole passage is based in the condition and 
supposed morphology of the swim-bladder. We have seen that undoubt- 
edly Am is one of the family of Lepidosteini, and hence its removal 
from the Ganoidei is impossible. 
The discussion of the rest of this quotation brings us to 
The interrelationships of Ganoidei, Selachii 
and Dipnoi. 
Prof. GEGENBAUR considers that both Ganoidei and Dipnoi 
were derived from Selachii. I have no idea whether or not the 
Dipnoi had a Selachian ancestry; if so, it can hardly have been 
from forms with the characters of the modern Selachii, i. e. with few 
large eggs etc. I am quite willing to admit that the Dipnoi are 
related, but very distantly, to the Selachii. 
As to the supposed origin of Ganoidei from Selachii that is’an 
impossibility; it would be nearer the truth to reverse the positions of 
the two groups, and to hold that the Selachii arose from the Ga- 
noidei. Indeed, I regard it as certain that the ancestors of the former 
were at one time allied to those of Ganoids in the conditions of such 
important organs as the brain and urinogenital organs. 
As those ancestors of the Selachii must have possessed holo- 
blastic eggs similar to those of the latter forms, we have further justi- 
fication for our views, for I know no evidence — not a tittle! — to 
show that the eggs of Ganoidei or Marsipobranchii ever pos- 
sessed more food-yolk than at present, or that they were meroblastic. 
Food-yolk is a precious possession for developing eggs: a form, which 
has once acquired it, will, as I think comparative embryology shows, 
only yield it up, if the greater advantages of certain food and protection 
afforded by intra-uterine development be proferred to it. An ultimate 
ancestry of all the fishes from the Selachii, as upheld by GEGEN- 
BAUR, iS just as erroneous as their derivation from Amphioxus. 
