The Challenger expedition was one of the great exploratory expeditions. The Radiolaria were described in the 'Scientific results of the Voyage of H.M.S. Challenger during the years 1873-1876, Report on the Radiolaria collected by H.M.S. Challenger by Ernst Haeckel, M.D., Ph. D. Professor of Zoology in the University of Jena'. The radiolaria formed volume 18 of 'Zoology'. An electronic version of the book is available here.
This image comes from the report of the Challenger expedition. Image out of copyright.