403 



ON A NEW SPECIES OF TECHN1TELLA FROM THE 

 NORTH SEA, WITH SOME OBSERVATIONS UPON 

 SELECTIVE POWER AS EXERCISED BY CERTAIN 

 SPECIES OF ARENACEOUS FORAMINIFERA. 



By Edward Heron-Allen, F.L.S., FR.M.S., 

 and Arthur Earland. 



(Bead April 2nd, 1909.) 



Plates 31 to 35. 



In the paper which we have the honour to submit to the Club 

 this evening, no attempt is made to explain either the processes 

 by which the tests of arenaceous foraminifera are constructed, 

 or the idiosyncrasies displayed by many of the genera and 

 species in the choice of their materials. But the discovery of 

 a species in the construction of whose test the utmost limit 

 hitherto observed, both as regards construction and selection, is 

 reached, has seemed a fitting opportunity to assemble and record 

 some of the facts that present themselves to the student whilst 

 observing these more or less highly specialised organisms. 



Before doing so, however, we will introduce the species to 

 which reference has been made. 



Sub-Kingdom . . . Protozoa. 



Class 

 Order 



Family III. 

 Sub-Family II. 



Rhizopoda. 



Foraminifera. 



astroriiizidae. 



PlLULININAE. 



Techrritella, Norman. 



Technitella thompsoni,* sp.n. 



Test free, sub-cylindrical, rounded and slightly tapering at one 

 extremity and bluntly truncate at the other, consisting of a 

 hollow chamber with composite w r alls built up entirely of 



* I am indebted to my friend Professor D'Arcy Wentworth Thompson, 

 C.B., F.R.S. , the Director of the International Committee for Investigation 

 of the North Sea (Scotland), for permission to publish the description 

 of this interesting form, and I have much pleasure in associating his name 

 with it in recognition of the many facilities which he has afforded me in 

 the progress of my work on the " Goldseeker," and in connection there- 

 with. — A. E. 



