296 THE VOYAGE OF H.M.S. CHALLENGER. 



Subgenus 1. Ellipsoxiphetta, Haeckel. 

 Definition. — Network of the shell regukr, with jiores of equal size and similar form. 



1. Ellii^soxiphus elegans, n. sp. (PI. 14, fig. 7). 



Proportion of the major axis of the ellipsoid to the minor = 5:4. Shell thick walled, with 

 regular, circular meshes, separated by a regular, hexagonal elevated framework. From each hexagon- 

 corner arises (between every three meshes) a short thin spine, about as long as the diameter of 

 a mesh ; twelve to fourteen meshes on the half equator, of the same breadth as the bars. Polar 

 spines three-sided prismatic, cuspidate, about as long as the axis of the shell. (This elegant and 

 not uncommon species is remarkable for its variations. By unequal development of both spines it 

 passes over to Ellipsosti/l !'■■?.) In the figured variety (PI. 14, fig. 7) the ends of the surface spines are 

 connected by a very delicate network, so as to form an outer veil. This may further be .separated 

 as a peculiar genus EWqisoxipliium jMlliatuvi. 



Dimensions. — Longer axis 0-08 to 01.3, shorter axis O'OG to Oil; pores and bars O'COS ; length 

 of the polar spines O'OG to 012, basal brea'dth 001. 



Habitat. — Pacific, central area, Stations 270 to 274, from 2350 to 2925 fathoms. 



2. Ellipsoxiphiis floficuhis, u. sp. 



Proportion of the major axis to the minor=6:5. Shell very thick waUed, with regular, 

 hexagonal meshes, eight to nine on the half equator, tlii'ee to four times as broad as the bars. The 

 inner contour of the meshes is circular, the outer sLx-loljed (similar to Xiphostijhis phasianiis, PL 13, 

 fig. 9). Polar spines three-sided pyramidal, about as long as the major axis of the shell ; their 

 basal thickness equals one mesh. 



Dimensions. — Longer axis 012, shorter axis 01; pores 0-012 to O'OIS, bars 01)04; length of 

 the polar spines 012 to 015, basal breadth 0-015. 



Habitat. — Fossil in the Tertiary rocks of Barbados (Teuscher). 



3. Ellipsoxiphus fragilis, n. sp. 



Proportion of the major axis to the minor = 4 : 3. Shell thin waUed, with regular, circular 

 meshes, twice as broad as the bars ; ten to twelve on the half equator. Surface smooth. I'olar 

 spines cylindrical, at the apex conical, half as long as the major axis. 



Dimensions. — Longer axis 0-16, shorter axis 0-12; pores O'OOS, bars 0-004; length of the 

 polar spines 0-09, basal breadth 0-008. 



Habitat. — South Atlantic, Station 325, surface. 



Subgenus 2. ■Ellipsoxipliilla, Haeckel. 

 Definition. — Network of the shell irregular, with pores of different size or form. 



