>IQ BULLETIN OP THE 



nseas, which are very voracious, could not find their accustomed 

 amount of food in such a restricted habitation, and were reduced 

 in size in consequence of their half-famished condition. He 

 cited other observations upon the lower animals which tended to 

 confirm the belief that insufficient food, through successive gene- 

 rations continuously, dwarfs the individuals of a species. 



He next remarked upon a characteristic of the genus Pleuro- 

 tomaria. This species of this genus all have a notch in the 

 aperture of the trochoid shell, and in some species this notch is 

 very deeply incised. The function of this notch in the economy 

 of the animal has been a matter of some doubt. Mr. Dall be- 

 lieved that its use was to permit the rejection of fecal products 

 when the animal is retracted into its shell. In many gasteropods 

 the anus is located in the anterior part of the soma, while in the 

 Pleurotomaridse this orifice is located behind the gills, and 

 would be covered by the shell when the body is retracted were 

 not a special modification of the shell-aperture provided. 



At the conclusion of Mr. Ball's communication the Society 

 adjourned. 



It 3d Meeting. January 11, 1880. 



Yice-President Welling in the Chair. 



Forty-one members present. 



The minutes of the last meeting were read and approved. 



The order of exercises for the evening consisted in the presen- 

 tation of communications from Messrs. M. H. Doolittle and 

 W. H. Dall. 



Mr. Doolittle's subject was 



A pile op balls. 



(abstract.) 

 Mr Doolittle's communication was a discussion of the appear- 

 ance the skv would present if the stars were of equal absolute 

 brilliancy, with a relative arrangement in space corresponding to 

 the centres of balls in a regular pile. The triangular and tlie 

 rectangular pile differ in respect to anterior only. The most 

 convenient Cartesian co-ordinate axes consist of the diagonals of 

 a square base with a perpendicular thereto. The most conve- 

 nient unit is equal to radius multiplied by the square root of 2 

 Then, the origin being at the centre of a ball, the centres of all 



