REPORT ON THE RADIOLARIA. 913 



3. Plagoniscus cortinaris, n. sp. 



Spines three-sided prismatic, straight, verticillate. Apical spine with twelve verticils, one and 

 a half times as long as the three basal spines, each of which bears eight verticils of three 

 branches. The branches are also prismatic, straight, on each edge parallel, tapering towards the 

 apex, hi the three basal spines forked, in the apical spine more branched. Similar to the cortinar 

 skeleton of Clathrocorys (PL 64, figs. 8-10). 



Dimensions. Length of the apical spine 0'24, of the basal spines 016. 



Habitat. South Atlantic, Station 338, surface. 



4. Plagoniscus nassellaris, n. sp. 



Spines cylindrical, curved, irregularly branched. Apical spine half as long as, and less branched 

 than the three basal spines, which are sigmoidal, nearly horizontally expanded in the proximal half, 

 descending in the distal half. 



Dimensions. Length of the apical spine 01, of the three basal spines 018. 



Habitat. West Tropical Pacific, Station 224, surface. 



Genus 388. Plagonidium,^ Haeckel, 1881, Prodromus, p. 424. 



Definition. P lagonida with four equal radial spines, arising in pairs from the 

 two poles of a common central rod. 



The genus Plagonidium and the following Plagiocarpa possess four radial spines, 

 like the two preceding genera. But whilst the four rods in these latter arise from a 

 common centre, here they arise in two pairs from the two poles of a common middle 

 rod ; they have therefore exactly the same form which we find in the single spicula of 

 some Beloidea (e.g., Thalassoxanthium furcatum, Spharozoum furcatum, &c.). 

 Probably the middle rod is horizontal and serves as supporting base for the central 

 capsule, whilst two opposite spines are directed upwards, two other downwards. 



1. Plagonidium bigeminum, n. sp. 



Spines straight, three-sided prismatic, four to six times as long as the common central rod, 

 pinnate, with four to five pairs of opposite pinnulse, the distal of which are simple, the proximal 

 again branched. 



Dimensions, Length of the spines 016, of the middle rod 0'032. 



Habitat. Indian Ocean, Sunda Strait (Rabbe), surface. 



1 Plagonidium = Small side-article ; jr^ttyuni^ioii. 

 CHALL. EXP. PART XL. 1886.) :Rr 115 



