CONTENTS OF VOL. XL PART I. 



Page 



1. — Wilson, E. B. Considerations on Cell-Lineage and An- 

 cestral Reminiscence, based on a Re-examination of 

 Some Points in the Early Development of Annelids 

 and Polyclades. (Figs. i-7), i 



2.— Trowbridge, 0. 0. An <' X-Ray Detector " for Re- 

 search Purposes. (Figs. 8- II), 29 



3. — Trowbridge, 0. 0. The Use of the Fluoroscopic Screen 



in Connection with Rontgen Rays. (Figs. 12-14), 39 



4. — Lloyd, Francis E. On Hypertrophied Scale-Leaves in 



Pinus ponderosa. (Plate I.) 45 



5. — HoUick, Arthur. Notes on Block Island. (Plates II.-IX.), 55 



6.— Dudley, P. H. The Use of the Dudley " Stremmato- 

 graph " in Determining Stresses in Rails under Mov- 

 ing Trains. (Plates X.-XIIL), 89 



APPENDIX. 



Catalogue of the Fifth Annual Reception and Exhibit, April 

 13, 14, 1898. 



