DEVELOPMENT OF THE SKULL OF THE COMMON FLOG. 
203 
perfectly in harmony with their surroundings as the highly specialized and noble Ganoid 
Fishes. Flow far these groups would tend to till up the space between the Ampliioxus 
and the simplest of their species, I need not say. Every anatomist will at once see that 
a creature no higher in type than the unhatched embryo of the Frog is yet an untold 
distance in advance of the Lancelet, which yet is only the Jcnown lowest of the great 
Vertebrate subkingdom. 
My next subject will be the Salmon, a sub typical “ Teleostean after that I hope to 
work out one of the lowest of the placental Mammalia, namely the Guinea-pig. 
The present paper has thrown some light upon the obscurer early stages of my last 
subject, the Fowl; this I have spoken of in the comparisons which have been made of 
the various types. 
Meantime, if any one desires to earn the lasting gratitude of morphologists, let him 
work out the development of a “Myxinoicl,” a Lamprey, or, still better, the Bdellostoma 
(see Muller’s “ Myxinoids,” pis. 1, 2, 3, 6, 7, 8). In the last type, especially, the labial 
cartilages, the facial cartilages and branchial “ basket,” the axial structures, and the sense- 
capsules — these might all receive the most beautiful and invaluable elucidations if the 
early stages were known of a creature so low in the scale and yet at the same time 
so intensely specialized and modified from its primordial condition. It is impossible 
for us not to search after the types that arose above the Lancelet ; and although they 
are most probably nearly all extinct , yet a clear comprehension of the stages of a Bdel- 
lostoma would give us pictures, diagrammatic indeed, but essentially true representatives 
of whole groups of lost “ Families” of the simpler types of Fish. 
This would be a new joy to the zoologist ; but to the morphologist it would be as a 
lamp, giving the light of a new life to his science ; and then would he be willing to break 
up his last idol, the mere creation of a fanciful transcendentalism, reasoning henceforth 
about the actual forms presented to him by Nature herself. 
9 T7 9 
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