530 PRIMARY FACTORS OF ORGANIC EVOLUTION. 



1886. Ryder, J. A. Annual Report U. S. Commissioner of Fish 



and Fisheries for 1884, pp. 981-1085, PI. IX. On the 

 Origin of Heterocercy, etc. 



1887. Ryder, J. A. American Naturalist, pp. 780-784. A Theory 



of the Origin of Placental Types, etc. 



1887. Cope, E. D. American Naturalist, pp. 985, 1060. The 



Perissodactyla. 



1888. Cope, E. D. Proceedings of the American Association for 



the Advancement of Science, p. 254. On the Mechanical 



Origin of the Sectorial Teeth of the Carnivora. 

 1888. Cope, E. D. American Naturalist, p. 3. The Mechanical 



Causes of the Origin of the Dentition of the Rodentia. 

 1888. Cope, E. D. Proceedings of the American Philosophical 



Society, p. 80. The Mechanical Origin of the Dentition 



of the Amblypoda. 



1888. Ryder, J. A. American Naturalist, p. 547. The Several 



Functions of the Enamel Organ in the Development of the 

 Teeth of Mammals, and on the Inheritance of Mutilations. 



1889. Cope, E. D. American Naturalist, March. The Artiodac- 



tyla. (The elbow-joint ; the zygapophyses.) 



1889. Cope, E. D. American Journal of Morphology, III., p. 137. 

 The Mechanical Causes of the Development of the Hard 

 Parts of the Mammalia. 



1889. Hyatt, A. Smithsonian Contributions to Knowledge, and 

 Memoirs of the Museum of Comparative Zoology, Cam- 

 bridge, XVI., No. 3. The Genesis of the Arietidae. 



1889. Ball, W. H. American Journal Science and Arts, XXXVIII., 

 p. 445. Hinge of Pelecypoda and Its Development. 



1889. Osborn, H. F. Transactions American Philosophical So- 

 ciety, XVI., p. 531. (Published February, 1890.) The 

 Evolution of the Ungulate Foot ; The Mammalia of the 

 Uinta Formation. 



1889. Ryder, J. A. American Naturalist, pp. 218-221. The Po- 

 lar Differentiation of Volvox, etc. 



1889. Ryder, J. A. American Naturalist, pp. 271-274. The Quad- 



rate Placenta of Sciurus hudsonius. 



1890. Ryder, J. A. Proceedings American Philosophical Society, 



XXVIII., pp. 109-159. The Origin of Sex, etc. 

 1890. Ryder, J. A. American Naturalist, pp. 376-378. The Pla- 



centation of the Hedgehog and Phylogeny of the Placenta. 

 1890. Packard, A. S. Proceedings Boston Society Natural His- 



