228 ORDER RADIO-FLA GELLA TA. 



as shown at Fig. 8, as well as by the temporarily modified posterior one that 

 usually fulfilled the office of a pedicle. Disengaging themselves from their single 

 or several points of attachment, the animalcules were frequently seen to swim freely 

 in the water with great rapidity after the manner of Oikomonas or Spumella. 



Fam. II. EUCHITONTD-ffi, S. K. 



Animalcules free-floating, secreting a variously constructed canccllate 

 siliceous test or lorica, which is distinguished by the invariable presence of 

 a central differentiated capsule ; ray-like pseudopodia extending from all 

 parts of the periphery, supplemented anteriorly by a comparatively large 

 and well-developed flagellate appendage. Entirely pelagic. 



As the members of this family possess characters that unite them more intimately 

 with the typical Radiolaria than with the ordinary Flagellata, a description of each 

 specific form is not included in this treatise, but a brief diagnosis only of a charac- 

 teristic representative of each generic group.* 



GENUS I. EUCHITONIA, Haeckel. 



Test siliceous, consisting of a flattened, biconvex, cyclically chambered, 

 central capsule, with radially developed projecting arms, which are dis- 

 posed in the same plane and chambered cyclically in correspondence with 

 the central disc ; the interspaces between the radiating arms filled in by 

 a loose, unsymmetrical, siliceous network. 



Euchitonia Virchowii, Hkl. PL. I. FIG. 24. 



Central capsule discoidal, with from two to three concentric chamber- 

 cycles ; radiating prominences three in number, their length slightly 

 exceeding the diameter of the central disc, the two* anterior slightly 

 narrower than the single isolated median posterior one, and basally 

 united ; cyclical chambers, of which the radiating arms are composed, 

 varying from four to six in number ; flagellum massive, equalling or 

 exceeding the length of the test, projecting from the angle between the 

 two anterior arms. Diameter of the central capsule 1-375". 



HAB. Pelagic : Messina. 



In addition to the foregoing type, as many as six other specific forms are referred 

 by Haeckel to the genus Euchitonia, in his magnificent monograph ' Die Radio- 

 larien,' Berlin, 1862, under the respective titles of E. -Bcskmanni, E. Gcgenbauri, 

 E, Krohnii, E. Muelleri, E. Leydigii, and E. Koellikeri. 



GENUS II. SPONGOCYCLIA, Haeckel. 



Test siliceous, consisting of a central capsule composed of concentric 

 and symmetrical chamber-cycles, surrounded by an irregular, sponge-like 

 lattice-work of siliceous trabeculae, this sponge-like lattice-work not deve- 

 loped peripherally into distinct arm-like processes. 



* Professor St. George Mivart recognizing the important distinction furnished by the presence 

 of flagella in the three genera included in this family division, has proposed ('Linnean Society's 

 Journal,' vol. xiv., No. 74, 1878) to separate them from the ordinary Radiolaria as a distinct section 

 of the " Flagellifera." 



