Discussion of the origin of vertebrates : January 20 and February 3, 1910 / by Dr. W.H. Gaskell [and others].
- Linnean Society of London
- Date:
- 1910
Licence: In copyright
Credit: Discussion of the origin of vertebrates : January 20 and February 3, 1910 / by Dr. W.H. Gaskell [and others]. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![The paramount importance of the development of the central nervous system for the upward progress of the members of the Animal Kingdom leads to the conclusion that each higher group of animals has arisen in succession from the highest race developed up to that time, by highest meaning the group possessing the best developed central nervous system. This law is proved to us most clearly by the evidence of the rocks in the case of the Vertebrate group. Thus we see that Man came from the Mammals, the highest race in the Tertiary times. They arose from the lieptiles, the highest race in Mesozoic times, who in their turn arose from the Amphibians, the lords of the Carboniferous epoch. Further back we leave the land and find that the Amphibians arose from the Fishes, the earliest of the Vertebrate race which swarmed in Devonian times. This steady sequence in upward progress from Fishes to Man, revealed by Gleology in the long series of ages from the Devonian to recent days, is in absolute conformity with the upward development of brain-power through tlie Vertebrate series from Fishes to Man, as shown by the investigations of Comparative Anatomists, especially Edinger and Elliot Smith. If thus it can be proved that such a law of Evolution has held good through the enormous spaces of time between the beginning of the Devonian and the present day, surely it is highly probable tliat the same law has held throughout, and that therefore the Fishes themselves arose from the race that was the most highly developed at the time when they first appeared; a race therefore which possessed a central nervous system most closely resembling that of the fish. The evidence of the rocks points to- the Silurian age as the time when the Vertebrate first arose, and to the great and ^riking group of Arthropods which swarmed in the seas at that time, to which the name Palaeostraca has been given. These were the highest developed race at that time and from them, according to this law of Evolution, the Vertebrate ought to have sprung. The great problem then for the study of the origin of Vertebrates resolves itself into this: What was the nature of the earliest fish and of the Palaeostraca in Silurian times ? That was the problem I set myself, and it is that comparison which 1 have attempted organ by organ in my recent book. Such an attempt was rendered possible by the fortunate occurrence of one of the Palaeostracan G-roup—Limulus or the King Crab—being still living in the present day, and what is still more important, the remarkable resemblance of Ammocoetes—tbe larval form of the Lamprey—to the fishes belonging to the Osteostraci, especially tiie close resemblance in position and structure of that remarkable muco-cartilaginous head-shield of Ammocceies to the head-shield of such a fish as Ce]>halaspis. My object throughout has been by the study of Amnnoccetes to find out a clue to the past history of these extraordinary early forms of fish. The results are published in my book, and give a](https://iiif.wellcomecollection.org/image/b22427387_0009.jp2/full/800%2C/0/default.jpg)
