C O N T E N T S. 
XXXI. On the Nature and Formation of Sponges : In 
a Letter from John Ellis, Efqutrej F. R. S. to 
Dr, Solander, F.R.S. p. 280. 
XXXII. RxtraB of a Letter from Dr. John Hope, 
Profejfor of Medicine and Botany in the Univerfty 
oj Edinburgh, to Dr. Pringle j dated Edinburgh, 
24 September, 1765, p. 290. 
XXXIII. Memoir^ containing the Hijiory of the 
Return of the famous Comet f 1682, with Ohfer- 
nations of the fame, made at Paris, at the Marine 
Obfervatory, in January, February, March, April, 
May, and the Beginning of June, 1759. By Mr. 
Meffier, jFironomer, Keeper of the journals. Plans, 
and Maps belonging to the Marine of France, Fellow 
of the Royal Society in London, and Member of the 
Society of Sciences m Holland ; tranfated jrom the 
French Matthew Maty, M. D. Sec. R. S. p. 294. 
XXXIV. On the Franfit of Venus in 1769, by the 
Rev, Mr. Hornfby, F. R. S. and Savilian Projeffor- 
f ^ronomy at Oxford, p. ^26. 
PHILO- 
