REPORT ON THE EADIOLARIA. 897 



Genus 382. Cystidium, 1 E. Hertwig, 1879, Organismus d. Eadiol., p. 87. 

 Definition. N assellida with hyaline calymma, without extracapsular alveoles. 



The genus Cystidium is the simplest and most primitive among all NASSELLARIA, 

 and may be regarded as the common ancestral form of this legion, for which it has 

 the same high importance as Actissa for the SPUMELLARIA. The central capsule is quite 

 simple, ovate or nearly spherical, and included in a voluminous hyaline calymma, which 

 contains no large alveoles. Cystidium differs from Actissa, its probable ancestral 

 form, in the possession of the " podoconus " and its basal " porochora," characteristic 

 of all NASSELLARIA or MONOPYLEA. 



1. Cystidium princeps, n. sp. (PL 91, fig. 1). 



Central capsule ovate, one and a third times as long as broad. Podoconus with simple 

 circular porochora, about half as long as the capsule, surrounded at its base by red granules of 

 pigment. Nucleus spherical. Three equal oil-globules in the endoplasm. No pigment in the 

 voluminous calymma, which includes numerous xanthellae. 



Dimensions. Length of the central capsule 01, breadth 0'075 ; nucleus 0'035. 



Habitat. Indian Ocean, Maldive Islands (Haeckel), surface. 



2. Cystidium lecythium, n. sp. 



Central capsule ovate, one and a half times as long as broad. Podoconus with simple circular 

 porochora, three-fourths as long as the capsule. Nucleus ellipsoidal. No oil-globules in the 

 endoplasm. No pigment and no xanthellae in the calymma. 



Dimensions. Length of the central capsule 0'12, breadth O08 ; nucleus 0'04 



Habitat. Central Pacific, Station 271, surface. 



3. Cystidium inerme, E. Hertwig. 



Cystidium inerme, R Hertwig, 1879, Organismus d. Radio!., p. 87, Taf. vii. figs. 1-16. 



Central capsule subspherical, a little longer than broad. Podoconus about two-thirds as long as 

 the capsule, with trifid porochora, which is composed of three equal circular lobes. Nucleus 

 spherical. Numerous oil-globules in the endoplasm. The calymma includes numerous xanthellse 

 and brown pigment around the mouth. 



Dimensions. Length of the central capsule 0'06, breadth 0'05 ; nucleus 0'03. 



Habitat. Mediterranean, Messina (R Hertwig), surface. 



1 Cystidium= Small vesicle ; xvirrKiov. 



(ZOOL. CHALL. EXP. PART XL. 1885.) Rr 113 



