EEPOET ON THE EADIOLARIA. 847 



2. Hylaspis coronata, n. sp. 



Parmal meshes five huiiih-ed to six hundred ; in the centre of each plate a cross of four long- 

 rectangular aspinal pores, between these four larger egg-shaped angular pores ; around this rosette 

 a circle of sixteen to twenty much smaller, irregular, roundish, coronal pores ; the latter about of 

 the same size as the sutural pores. On each condyle one bearded by-spine about one-third 

 or one-fourth as long as the radius. Twenty radial spines, very long, smooth, quadrangular, 

 prismatic. 



Dimensions. — Diameter of the shell 0'25, aspinal pores 0'02, other pores 0'005 to O^Ol, bars 

 0-004 



Hahitat. — Central Pacific, Station 271, surface. 



3. Hylaspis harhata, u. sp. 



Parmal meshes twelve hundred to sixteen hundred ; in the centre of each plate a cross of four 

 large, somewhat oblong, octahedral aspinal pores, between these four rhombic smaller angular pores ; 

 around this rosette an inner circle of twelve to sixteen larger and an outer circle of fifty to sixty 

 very small coronal pores ; the latter smaller than the sutural pores. On each condyle one bristle- 

 shaped zigzag by-spine, with recurved thin hooks, half as long as the radius. Twenty radial spines, 

 very long, cylindrical, smooth. 



Dimensions. — Diameter of the shell 0-25 to 0-3, aspinal pores 0'022, other pores 0-002 to 0-015, 

 bars 0-002. ' 



Habitat. — South Pacific, Station 295, surface. 



Family X LI. P h R acto p E lt id a, Haeckel (PI. 133, figs. 1-6). 



Pkradopeltida, Haeckel, 1881, ProJromus, p. 468. 



Definition. — Acantharia with double spherical lattice-shell, composed of the 

 branched apophyses of twenty radial spines meeting in its centre, and disposed according 

 to the Miillerian law of Icosacantha. Central capsule spherical, enclosing the inner 

 and surrounded by the outer concentric shell. 



The family Phractopeltida differs from all other Acantharia in the develop- 

 ment of a double spherical shell, composed of two concentric lattice-spheres, which are 

 united by twenty radial spines meeting in the common centre. We could therefore 

 oppose the Phractopeltida as Diplophracta to all other A c a n t h o p h r a c t a as 

 Haplophracta (with simple shell). The former exhibit a relation to the latter, similar 

 to that exhibited by the Dyosphserida to the simple Monosphaerida among the 

 S p h 86 r i d e a. 



In my Monograph (1862, p. 423) I described only one genus appertaining to this 

 family, Aspidomma. I founded it upon the singular Phractopelta, described by 



