REPORT ON THE RADIOLARIA. 355 



Genus 152. Artiscus, 1 Haeckel, 1881, Prodromus, p. 462. 



Definition. A rtiscida without peculiar polar appendages (without strong solid 

 spines or hollow fenestrated tubes on the poles of the main axis). 



The genus Artiscus represents the most simple and primitive form of the Artiscida, 

 and may therefore be regarded as the ancestral form of this subfamily. It resembles 

 an ordinary double loaf, composed of two equal, nearly ellipsoidal fenestrated shells 

 separated by the stricture in the equatorial plane. Artiscus can be derived from 

 Cenellipsis simply by this equatorial constriction. But it can also be derived from 

 Cyphanta by loss of the medullary shell. 



Subgenus 1. Artiscium, Haeckel. 

 Definition. Surface of the shell smooth or rough, without radial rods or spines. 



1. Artiscus paniscus, n. sp. 



Pores of the shell regular, hexagonal, four times as broad as the bars ; ten to twelve pores on 

 the half meridian, eight to nine on the half equator. Surface smooth. (The network of this species 

 is quite the same as that of the proximal camera? of Panartus diploconus, PI. 40, fig. 1.) 



Dimensions. Main axis of the shell O12, equatorial axis O07 ; meshes 0'013, bars O'OOS. 



Habitat. Pacific, central area, Station 271, depth 2425. 



2. Artiscus facetus, n. sp. 



Pores of the shell regular, circular, with prominent hexagonal frame, twice as broad as the bars: 

 twenty-two to twenty-four pores on the half meridian, fourteen to fifteen on the half equator. 

 Surface a little thorny. (The shell of this species exhibits nearly the same formation as that of 

 Cyphonium virgineum, PI. 39, fig. 12, but without enclosed medullary shells.) 



Dimensions. Main axis of the shell 0'15, equatorial axis O09 ; meshes O'Ol, bars O'OOS. 



Habitat. Pacific, central area, Station 266, depth 2*750 fathoms. 



3. Artiscus paniculus, n. sp. 



Pores of the shell regular, circular, without hexagonal frame, as broad as the bars ; fourteen to 

 sixteen pores on the half meridian, ten to eleven on the half equator. Surface quite smooth. 

 Dimensions. Main axis of the shell 0'13, equatorial axis 0'06 ; meshes O'Ol, bars O'Ol. 

 Habitat. Fossil in the Tertiary rocks of Barbados (Haeckel). 



1 Artiscus = Small loaf ; d^riaxos. 



