ON CHANGES DURING A SOLAR-SPOT PERIOD. 137 



Sponge-spicula. 



References to the Memoir. Modern Nomenclature. 



Plate IV. 

 f. 81. Sponge-spiculutn ? (p. 80) Sponge-spiculum. 



82. Ditto, calcareous (p. 80) Ditto, calcareous. 



83. Ditto, siliceous (p. 80) Ditto, siliceous. 



Shell-structures. 



f.84. lamina of shell-structure {Inoce- j Lamina of /w ^ mwws (she ll). 

 ramus ?) (p. 80) J 



85. Detached prisms of ditto (p. 80) ... Prisms of ditto. 



86. Ditto (p. 80) Ditto. 



XVI. On Changes in the Distribution of Barometric Pres- 

 sure, Temperature, and Rainfall under different Winds 

 during a Solar-spot Period. By Joseph Baxendell, 

 F.R.A.S. 



Read before the Physical and Mathematical Section, November 7th, 187 1. 



In my paper "On Periodic Changes in the Magnetic 

 Condition of the Earth, and in the Distribution of Tem- 

 perature on its Surface/' read March 8, 1864, I endea- 

 voured to account for some of the phenomena therein 

 described by assuming that variations in the magnetic 

 condition of the earth produce corresponding variations 

 in the direction and velocity of the great currents of the 

 atmosphere ; and some time afterwards, in considering this 

 hypothesis more carefully, it appeared to me that if, as is 

 generally supposed, magnetic changes are intimately con- 

 nected with the disturbances which take place in the solar 

 photosphere, their influence upon the atmosphere ought 

 to be indicated by variations in the distribution of baro- 



