REPORT ON THE RADIOLARIA. 1631 



2. Auloplegma spongiosum, n. sp. (PI. Ill, fig. 9). 



Radial tubes slender, straight, cylindro-conical, studded irregularly with lateral branches, which 

 are short, simple, slightly curved, partly verticillate in the distal third, and ending with a small 

 spinulate knob. The length of the radial tubes is about twice as great as the radial diameter of the 

 spongy framework, which forms the wall of the spherical shell, and is composed of thorny or verti- 

 cillate cylindrical tubes. 



Dimensions. Diameter of the shell 3'2, of its wall O'l ; length of the radial tubes 0'24, 

 breadth O'Ol. 



Habitat. North Pacific, Station 231, surface. 



Genus 686. Aulophacus, 1 n. gen. 



Definition. A ulosphserida with triangular meshes in the network, the 

 tangential tubes of which form a simple, lenticular, biconvex lattice-shell, with 

 shortened vertical main axis. Radial tubes arise at its nodal points. 



The genus Aulophacus differs from the common Aulosphcera, its ancestral form, 

 only in the lenticular compression of the spherical lattice-shell, the vertical axis of 

 which is considerably shortened. It exhibits therefore to the latter the same relation 

 as Cenodiscus does to Cenosphcera among the Sphseroidea. The contrary condi- 

 tion is shown in the following genus Aulatractus, in which the vertical axis is prolonged. 

 In the two species of Aulophacus observed the radial spines exhibit a remarkable 

 peculiarity, being longer on the circular periphery of the lens, shorter on both its faces, 

 and shortest in the vertical main axis. 



1. Aulophacus lenticularis, n. sp. (PI. Ill, fig. 5o). 



Shell biconvex, lenticular, with rounded circular margin ; its horizontal diameter three times 

 as great as its thickness (or its vertical main axis). Radial tubes cylindro-conical, straight, with 

 six to nine triradiate verticils, those of the margin of the lens twice as long as the smooth tangential 

 tubes, the others shorter. 



Dimensions. Horizontal diameter of the lens 5'5 mm., vertical main axis 0'2 ; length of the 

 radial tubes 0'2, breadth O'Ol. 



Habitat. Indian Ocean, Belligemma, Ceylon (Haeckel) surface. 



2. Aulophacus amphidiscus, n. sp. (PI. Ill, fig. 56). 



Shell discoidal, slightly biconvex, with rounded circular margin ; its horizontal diameter five 

 times as great as its thickness. Radial tubes cylindrical, covered with numerous short thorns, those 

 of the margin of the lens three times as long as the smooth tangential tubes, the others shorter. 



1 Aulophacus = Tubular lens ; <*iXo;, 



