EEPORT ON THE EADIOLARIA. 503 



Dimensions. — Diameter of the disk (with three rings) 0'12 ; breadth of each ring 0'016 ; 

 pores 0'004 



Habitat. — -South Pacific, Station 302, depth 1450 fathoms. 



2. Stomatodiscus osculatvs, n. sp. (PI. 48, fig. 8). 



Disk elliptical, nearly twice as long as broad, with three concentric rings around the elliptical 

 central chamber, one piercing radial beam in the main axis, the other beams interrupted. Surface 

 of the shell with small scattered thorns. Pores very irregular, roundish, partly aggregated in 

 groups of four to eight smaller porules. On both poles of the main axis a large elliptical marginal 

 osculimi, about as large as the central chamber, armed with a coronet of short conical spines. 



Dimensio7is. — Length of the disk (with three rings) 0"18, breadth 01 ; pores O'OOl to 0'006. 



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



Subfamily 4. Stylodictyida, Haeckel, 1881, Prodromus, p. 459. 



Definition. — P o r o d i s c i d a vAt\\ solid radial spines ou the margin of the 

 concentrically annulated disk, situated in the equatorial plane of the disk (without 

 chambered arms and marginal oscula). 



Genus 218. Xiphodictya^ Haeckel, 1881, Prodromus, p. 460. 



Definitio7i. — P orodiscida with two opposite, solid, radial spines on the margin 

 of the circular or elliptical disk. 



The genus Xiphodictya opens the series of the Stylodictyida or of those Porodiscida 

 in which the margin of the chambered disk is armed with solid radial sjiines, all 

 situated in the equatorial plane of the disk. Xiphodictya exhibits the minimum 

 number of spines, two being opposite on the poles of one equatorial axis of the disk. 

 It repeats, therefore, in this family the same amphistylic formation as Sethostylus in 

 the Phacodiscida and Stylocyclia in the Coccodiscida. 



Subgenus 1. Xiphodictyon, Haeckel. 

 Definition. — All rings of the disk concentric, cii'cular. 



1. Xiphodictya amphihelonia, n. sp. (PI. 42, fig. 10). 



All rings of the disk concentric, circular, of equal breadth. Pores irregular, roundish, one and 

 a half to two on the breadth of each rmg. Margin of the disk thorny, of the same thickness as 



' Xiphodictya='Set with swords ; l/ipos-, Iiktvo». 



