172 Prof. Ehrenberg on Microscopic Life 



Lastly, Elic dc Beaumont, in 1841, adopted the o])inion, that 

 the limits to wliich tlie waters of the sea had been found by Siau 

 capable of being set in motion, must be also those at which ses- 

 sile marine animals could exist, since these have to wait for their 

 food, which in this way only could be conveyed to them, and that 

 consequently the limits of stationary organic life, taken in con- 

 junction with the depth of the waves, could not much exceed 

 200 metres or 600 foot. 



Such considerations, deeply affecting the general science of 

 geology, and to which must be added observations upon the in- 

 crease of temperature towards the centre of the earth, have ever 

 suggested as an interesting matter for inquiiy to the author, to 

 examine minute organic life in relation to the depth of the ele- 

 ment in which it could exist. 



Science indeed owes a great debt of gratitude to those travel- 

 lers who have so industriously provided the materials of this 

 investigation ; in respect of which materials it may be observed 

 generally, that they are very rich in quite new typical forms, 

 particularly in genera, of which some contain several species; 

 these, occasionally with some mud and fragments of small crus- 

 taceans, form the chief part of the mass. The new genera* and 

 species are here recorded, and of these the Astet-omphali are very 

 remarkable, from their particularly beautiful stellate forms. 



Analysis of the various materials furnished hij Dr. Hooker from 

 the South Polar Voyage. 



1. Residue from some melted Pancake Icef at the barrier in 

 78° 10' S. lat., 162° W. long. 



A. SILICEOUS POLYGASTRICA. 



* Of tlie 7 new genera of Polygastrica, viz. Anaulus, AsterompJiahis, Chce- 

 toeeros, Halionyx, Hendaulus, Hemizoster, and TrianlaciaSy short characters 

 are given in the Proceedings of the Academy: also of the 71 new species. 



f Thin and level fragments of ice found Heating in the ocean. 



