REPORT ON THE RADIOLARIA. 977 



The genus Eucoronis and the following two nearly allied genera (Plectocoronis and 

 Podocoronis) compose together the important subfamily Eucoronida. In this typical 

 main group of Coronida the shell is constantly composed of three rings and six gates. 

 The vertical sagittal ring and the horizontal basal ring are complete (as in the Semantida); 

 the vertical frontal ring is incomplete. Between these three rings remain six large 

 open gates, the four upper (or lateral) are always much larger than the four lower 

 (or basal gates). Eucoronis may be derived from Semantis by development of the 

 frontal ring. 



Subgenus 1. Acrocoronis, Haeckel, 1881, Prodromus, p. 445. 

 Definition. Kings smooth or rough, armed with numerous short spines or thorns. 



1. Eucoronis perspicillum, n. sp. (PL 82, fig. 6). 



Frontal ring elliptical, twice as broad as high, with a slight constriction at the apical pole, 

 armed with three pairs of short conical spines, one apical pair (near the constriction) and two 

 lateral pairs (one upper and one lower pair). Sagittal ring of the same height, half the breadth 

 and double the thickness, also armed with three pairs of spines (one basal, one dorsal, and one 

 ventral pair). 



Dimensions. Height of the frontal ring OH, breadth 0'22. 



Habitat. Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms. 



2. Eucoronis Icevigata, n. sp. 



Frontal ring elliptical, smooth, one and a half tunes as broad as high, without sagittal constric- 

 tion, with horizontal basal gates. Sagittal ring of the same height and thickness, also elliptical 

 and smooth. No spines on either of the smooth rings. 



Dimensions. Height of the frontal ring 01, breadth 015. 



Habitat. Western Tropical Pacific, Station 225, depth 4475 fathoms. 



3. Eucoronis nephrospyris, n. sp. (PL 82, fig. 5). 



Frontal ring kidney-shaped, in the upper half convex, in the lower concave, with a sagittal 

 constriction (often much deeper than in the specimen figured). Sagittal ring ovate, about two- 

 thirds as high as the frontal ring. Eods of both rings without edges, cylindrical, armed with 

 numerous short conical thorns. 



Dimensions. Height of the frontal ring 01 to 012, breadth 015 to 018. 



Habitat. Cosmopolitan ; Mediterranean, Atlantic, Indian, Pacific, many Stations, surface and 

 at various depths. 



(ZOOL. CHALU EXP. PART XL. 1886.) Rr 123 



