Report on the Radiolaria Collected by H.m.s. Challenger During the Years 1873-1876, Second Part: Subclass Osculosa; Indexreport on the Scientific Results of the Voyage of H.m.s. Challenger During the Years 1873-76, Vol. XVIII

A scientific publication written in the late 19th century. This work is a detailed examination of radiolarians, a group of protists characterized by their intricate silica-based skeletons, based on specimens collected during the celebrated Challenger expedition. Haeckel's comprehensive analysis includes descriptions of various genera and species, their morphology, and classifications within the broader context of zoological studies. The beginning of this publication presents extensive introductory material, laying the groundwork for understanding the findings regarding radiolarians. Haeckel describes the overall framework of the study, outlining the various subcategories of radiolarians and introducing the complex classification system he has developed. It delves into the nuances of their structural characteristics, such as the distinctive features of their skeletons, and establishes a categorized approach to exploring the diversity and evolutionary significance of the collected specimens. This opening serves as a precursor to the detailed accounts of specific radiolarian forms that follow in the subsequent chapters.