TRANSACTIONS 



OF THE 



American Philosophical Society 



Held at Philadelphia, 

 For Promoting Useful Knowledge. 



Vol. XX, Nezv Series. Part I, ^to, pp. 62, with 3 Plates. 



Lately Published. 



CONTENTS. 



Art. I. — The History of the Pelycosauria, with a Descrip- 

 tion of the Genus Dimetrodon Cope. By G. 

 Baur and E. C. Case. 



Part II. 4to, pp. 1 7 y, with 5 Plates. 

 Just Published. 



CONTENTS. 



Art. II. — The Chronological Distribution of the Elasmo- 

 branchs. By O. P. Hay. 



Art. III. — Results of Observation with the Zenith Telescope 

 of the Sayre Observatory from January 19, 1894, 

 to August 19, 1895. By Charles L. Doolittle. 



Art. IV.— A Study of the Chromosomes of the Germ Cells 

 of Metazoa. By Thomas H. Montgomery, Jr., 

 Ph.D. 



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Address THE LIBRARIAN OF THE 



American Philosophical Society, 



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Philadelphia, U. S. A. 



