PARALLELISM AND CONVERGENCE 979 



which related animals or plants have developed in a similar man- 

 ner but independently and those in which unrelated animals or 

 plants have developed similar characteristics which apparently 

 bring them more closely together. To the former the term parallel- 

 ism has generally been restricted, while the term convergence has 

 been applied to the latter case. Of course, it is understood that 

 the use of this term does not imply that the organisms in question 

 actually converge in their relationship, as seems to have been as- 

 sumed by some, but merely that the convergence is only a morpho- 

 Jogic one and may lead to mistaken ideas of relationship. The 

 similar independent development of the projecting flange in the 

 species of Clavilithes, cited above, may be considered a case of 

 pure parallelism, while its development in Rhopalithes may be con- 

 sidered a case of convergence. A similar case of convergence is 

 seen in the American Eocenic Falsifusus and the British Eocenic 

 Fusus, already cited, both of which have adult characteristics which 

 have led to their being classed in the same genus. That they are of 

 independent ancestry, however, seems to be established.* 



BIBLIOGRAPHY XXV. 



1. BEECHER, CHARLES E. 1901. Studies in Evolution. Charles Scrib- 



ner's Sons, New York. 



2. BUCKMANN, S. S. 1909. Yorkshire Type Ammonites. 



3. CLARK, WILLIAM B. 1910. Contributions to Morphology from Pale- 



ontology. The Paleontological Society Conferences on the Aspects of 

 Paleontology. First Annual Meeting, Cambridge, Mass. Dec. 29, 1909. 

 Reprinted from Popular Science Monthly, June to November, 19 10. 



4. CUMINGS, EDGAR R. 1903. The Morphogenesis of Platystrophia, a 



Study of the Evolution of a Palaeozoic Brachiopod. American Journal 

 of Science, 4th series, Vol. XV, pp. 1-48, 121-136. 



5. CUMINGS, E. R. 1904. Development of Some Palaeozoic Bryozoa. 



Ibid., Vol. XVII, pp. 49-78. 

 5a. CUMINGS, E. R. 19 10. Paleontology and the Recapitulation Theory. 

 The Paleontological Record, pp. 57-63, Reprinted from Popular Science 

 Monthly. Ibid. Proceedings of the Indiana Academy of Science, 1909 

 Meeting, pp. 1-36. 



6. DE VRIES, HUGO. 1901. Die Mutations-theorie. Leipzig. 



7. DE VRIES, H. 1905. Species and Varieties. Their Origin by Mutation. 



Open Court Publishing Company, Chicago. 



8. D'ORBIGNY, ALCIDE. 1840. Palaeontologie Frangaise. Terrains, 



Cretaces Cephalopodes. Paris. 



9. EIMER, TH. 1898. On Orthogenesis, and the Impotence of Natural 



Selection in Species-forming. Open Court Publishing Company, Chicago. 



10. FARLOW, W. G. 1898. The Conception of Species as Affected by Recent 



Investigations on Fungi. Vice-Presidential Address before the American 



Association for the Advancement of Science, 1898. Section of Botany. 



* See the controversy above referred to. 



