Ryder.] ^^^ [April 7, 



are not invariably to be depended upon, owing to the very different inter- 

 pretations now to be given man,y of them. Papers by Cope on the me- 

 chanical development of the structure of the hard parts, teeth and joints, 

 are to be found in tlie Avierican Naturalint, Journal of Morphology and 

 Proc. Amcr. Philos. Soc. Prof. Hyatt has also published several import- 

 ant papers on this subject, especially in reference to Molluska. Suggest- 

 ive papers have also been published in this connection by Dr. W. H. Dall, 

 while Lang has considered the development of the shells of univalve 

 mollusks from a mechano-physiologlcal standpoint in his Lehrbuch d. 

 Vergleic7iende7i Anatomie. 



Purely physical papers by Plateau, Mensbrugghe, Quincke and others 

 are also important as well as the experimental and biological results pub- 

 lished by O. Biitschli and H. Virchow. 



The subjoined list of papers by the author of the foregoing paper em- 

 braces the principal part of wliat he has published upon the ergogenelic 

 development of morphological characters in the animal kingdom : 



On the Laws of Digital Reduction, Am. Naturalist, 1877, pp. 603-607. 



Nature, xvii, 1877, p. 128. 



On the Mechanical Genesis of Tooth-forms, Proc. Acad. Nat. Sciences, 

 Philadelphia, 1878, pp. 45-80 (Abstr. by C. N. Peirce). 



Dental Cosmos, xx, 1878, pp. 465-472. 



Further Notes on the Mechanical Genesis of Tooth-forms, Proc. Acad. 

 Nat, Sciences, Philadelphia, 1879, pp. 47-51. Review of by E. D. Cojie, 

 Am. Naturalist, 1879, pp. 446-449. 



On the Origin of Bilateral Sj^rametry and the Numerous Segments of 

 the Soft Rays of Fishes, Am. Naturalist, xiii, 1879, pp. 41-43. 



The Gigantic Extinct Armadilloes and Their Peculiarities, With a Res- 

 toration, Pop. Sci. Monthly, xiii, pp. 139-145. 4 figs. [Discusses the 

 mechanical genesis, degeneration, and coalescence of vertebral centra.] 



The Significance of the Diameters of the Incisors of Rodents, Proc. 

 Acad. Nat. Sciences, Philadelphia, 1877, pp. 314-318. 



On the Position of the Yolk-blastopore as Determined by the Size of 

 the Vitellus, Am. Naturalist, 1885, pp. 411-415. 



On the Availability of Embryological Characters in the Classification 

 of the Chordata, Am. Naturalist, 1885, pp. 815-819 and 903-907. 



On the Genesis of the Extra Terminal Phalanges in the Cetacea, Am. 

 Naturalist, 1885, pp. 1013-1016. 



An Outline of a Theory of the Development of the Unpaired Fins of 

 Fishes, Am. Naturalist, 1885, pp. 90-97. 



The Origin of the Amnion, Am. Naturalist, 1886, pp. 179-185. 



On the Origin of Heterocercy, etc., Ann. Rep. U. S. Com. of Fish and 

 Fisheries for 1884, pp. 981-1085, PI. ix, 18S6. 



A Theory of the Origin of Placental Types, etc.. Am. Naturalist, 1887, 

 pp. 780-784. 



'On the Homologies and Early History of the Limbs of Vertebrates, 

 Proc. Acad. Nat. Sciences, Philadelphia, 1887, pp. 344-386. 



