516 PROCEEDINGS OP THE AMERICAN ACADEMY. 



Exhibition and Preliminary Account of a Collection of Micro- 

 photographs of Snow Crystals, made by W. A. Bentley. By 

 John E. Woltf. 



Albert A. Michelson exhibited and described a new form of 

 spectroscope. 



The following papers were read by title : — 



Contributions from the Zoological Laboratory of the Museum 

 of Comparative Zoology : A Contribution to the Study of Indi- 

 vidual Variation in the Wings of Lepidoptera. By W. L. W. 

 Field. Certain Sense Organs of the Proboscis of Rhyncho- 

 bolus dibranchiatus. By A. Oppenheimer. Presented by E. L. 

 Mark. 



Contributions from the Gray Herbarium of Harvard Uni- 

 versity. New Series. No. XIV. — By J. M. Greenman. I. Re- 

 vision of the Mexican and Central American Species of Galium 

 and Relbunium. II. Diagnoses of New and Critical ]\Iexican 

 Phanerogams. Presented by B. L. Robinson. 



An Absolute Measurement of the Thomson Effect in Copper. 

 By R. O. King. Presented by E. H. Hall. 



Note on Stokes's Theorem in Curvilinear Co-ordinates. By 

 A. G. Webster. 



Note on the Projective Group. By E. W. Rettger. Pre- 

 sented by Henry Taber. 



On the Thermal Conductivities of Certain Poor Conductors. 

 By B. 0. Peirce and R. W. Willson. 



