•  
  •  
 

Authors

H. W. Norris

Document Type

Research

Abstract

In the struggle for existence as individuals the Amphibians, or Batrachians, seem to have a minor position. For the most part of insignificant size, with poorly protected bodies, and with retiring and inoffensive habits, these forms which we know as toads, frogs and salamanders, seem to be poorly adapted to maintain their species. From what the paleontologist tells us, we may well believe that the Amphibians as a class arose, flourished, and then declined to their present insignificant proportions long ago. It is because of the relationships of this group that it is of profound interest to science. It forms a connecting link, or rather a series of connecting links between the strictly aquatic Vertebrates, the Fishes, and the terrestrial forms. Presenting two distinct phases, a larval aquatic and an adult terrestrial condition, it presents for our observation the actual evolution of an aquatic, branchiate form into a terrestrial pulmonate form. Furthermore some forms retain the branchial organs throughout life, while others hardly give us a hint of a much shortened aquatic stage. This metamorphosis is not merely superficial, but is accompanied by profound morphological and functional changes.

Publication Date

1900

Journal Title

Proceedings of the Iowa Academy of Sciences

Volume

8

Issue

1

First Page

76

Last Page

78

Copyright

© Copyright 1900 by the Iowa Academy of Science, Inc.

Language

en

File Format

application/pdf

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.