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



11. Druppatractus pisciculus, n. sp. 



Cortical shell thick walled, spiny, 'with irregular network. Proportion of the two axes = 3:2. 

 Pores irregular, roundish, lobed, or composed of three to five confluent porules, twice to six times 

 as broad as the bars ; six to eight on the half equator. (Similar to Ellipsoxiplius atractus, PI. 14, 

 fig. 1.) Medullary shell ellipsoidal, nearly half as large as the cortical shell. Polar spines three- 

 sided pyramidal, the major longer than the main axis, the minor scarcely one-third to one-fourth as 

 long. 



Dimensions. Major axis O'lS, minor 012; pores O'Ol to 0'03, bars O004 ; axes of the 

 medullary shell 0'08 and 0'05 ; length of the major polar spine 0'2, of the minor 0'05, basal 

 breadth 0'02. 



Habitat. South Atlantic, Station 332, depth 2200 fathoms. 



Genus 139. Stylatractus,* 11. gen. 



Definition. D ruppulida with simple ellipsoidal cortical shell and double 

 medullary shell, in the main axis with two large opposite polar spines of equal size 

 and similar form. 



The genus Stylatractus differs from Lithatractus in the double medullary shell, 

 from Amphisphcera in the ellipsoidal form of the cortical shell. As in these two 

 genera, both opposite polar spines have the same shape and size. 



Subgenus 1. Stylatractara, Haeckel. 



Definition. Network of the cortical shell regular or subregular, with meshes of 

 nearly equal size and similar form ; surface smooth, without thorns or papillae. 



1. Stylatractus neptunus, n. sp. (PI. 17, fig. 6). 



Ampltistylus neptunus, Haeckel, 1878, Atlas, pi. xvii. fig. 6. 



Cortical shell thick walled, smooth, with subregular, circular, polygonally framed pores, quite as 

 broad as the bars ; ten to twelve on the half equator. Polar spines three-sided pyramidal, about as 

 long as the half main axis, three times as broad at the base as the pores. (Much resembles 

 Amphisphcera neptunus, p. 142, but differs from it by the prolongation of the main axis, which 

 equals one and a half or one and a fourth the equatorial axis, and by the somewhat irregular 

 formation of the cortical hexagonal network. Sometimes also, as in the figured specimen, the 

 length of both polar spines is somewhat different.) 



Dimensions. Major axis of the cortical shell 015, minor axis 012 ; pores and bars O'OOT ; main 

 axes of both ellipsoidal medullary shells 0'08 and - 05 ; length of the polar spines 0'08 to 01, 

 basal breadth 0'02. 



Habitat. Pacific, central area, Stations 266 to 268, depth 2700 to 2900 fathoms. 

 1 Stylatractus = Spindle with styles ; HTV^O;, Ar^ax.;. 



