REPORT ON THE RADIOLARIA. 1467 



Family LXX. LITHOCAMPIDA, n. fam. 



Artocorida et Artocapsida, Stichocorida et Stichocapsida, Haeckel, 1881, Prodromus, pp. 437-439. 



Definition. S tichocyrtida eradiata. (Cyrtoidea with an annulated 

 shell, divided by three or more transverse constrictions into four or more annular 

 joints, without radial apophyses.) 



The family Lithocampida comprises those Cyrtoidea in which the 

 lattice-shell is composed of numerous (four to eight or more) annular joints, and bears 

 no radial apophyses. It may be divided into two subfamilies, differing in the shape 

 of the terminal mouth. This is a simple wide opening in the Stichocorida (and the 

 united Artocorida), closed by a lattice-plate in the Stichocapsida (and the allied 

 Artocapsida). The phylogenetic origin of the Lithocampida may be found in the 

 Theocyrtida. 



The number of species of Lithocampida is very great, and amounts here to more 

 than one hundred and sixty, whilst the total number of Stichocyrtida is about two 

 hundred and forty. They represent, therefore, two-thirds of the whole group, whilst 

 one-third is composed of the Podocampida and Phormocampida. Ehrenberg has 

 already described between forty and fifty species in his genera Eucyrtidium and Litho- 

 campe; the majority of these were fossils from Barbados. 



This large number of species may be easily increased by accurate researches on the 

 great masses of Lithocampida, which are found in the Radiolarian ooze of the 

 Challenger, and as fossils in Barbados. The variety in the number, size, and proportion 

 of the shell-joints and of the lattice-pores is very great, and permits us to distinguish a 

 far greater number of species than are here described. Many species are cosmopolitan, 

 and belong to the most common forms of Radiolaria. 



This large number of species requires to be disposed in different genera, but 

 the distinction of these latter is a rather difficult task, since the exterior of the shell, as 

 well as its internal structure, offers no striking differences (compare Pis. 78 to 80). In 

 my Monograph (1862, pp. 312 to 319) I have already pointed out the difficulty of 

 distinguishing between Lithocampe and Eucyrtidium. The general form of the shell 

 exhibits a continuous series of transformations, from a flat, conical, or nearly discoidal 

 form, through cylindrical to ovate, or spindle-shaped shells, the wide open terminal 

 mouth becoming more or less constricted, and finally (in the Stichocapsida) closed. 

 The absence .or presence of an apical horn may further serve for the distinction of 

 genera. A peculiar small group is represented by the Spirocampida (Spirocyrtis, 

 Spirocampe, PL 76, figs. 11 to 17), the transverse latticed girdles separating the single 

 joints, which are usually parallel and horizontal, becoming here partly connected, so 

 that they form a descending spiral. 



