1394 THE VOYAGE OF H.M.S. CHALLENGER. 



both poles, and resembles greatly the triradiate Rhopalocanium. It may be derived 

 from the latter by interpolation of three secondary or interradial wings between the 

 three primary or perradial apophyses. 



1. Hexalatractus sexalatus, n. sp. 



Shell ovate, smooth, with two distinct strictures. Length of the three joints = 3:6:9, breadth 

 = 4:9:8. Cephalis subspherical, with a pyramidal horn of twice the length. Thorax campanu- 

 late ; abdomen inversely conical ; both with subregular, circular pores. Six divergent wings arise, 

 beginning from the collar stricture, from the upper half of the shell, with broad triangular base ; 

 they are little curved downwards, with the convexity outside, and gradually tapering towards the 

 distal end ; the latter lies in the same horizontal plane as the basal apex of the abdomen. 



Dimensions. Length of the three joints, a 0'03, b 0'06, c O09 ; breadth, a 0'04, I 0'09, c 0-08. 



Habitat. Central Pacific, Stations 263, depth 2650 fathoms. 



2. Hexalatractus fusiformis, n. sp. (PI. 68, fig. 13). 



Shell rough, nearly spindle-shaped, with sharp collar and slight lumbar stricture. Length of the 

 three joints = 2:5:12, breadth = 3:8:7. Cephalis hemispherical, with a conical horn of the same 

 length. Thorax hemispherical, with regular, circular, hexagonally-framed pores. Abdomen 

 inversely conical, with irregular, roundish pores. From the upper half of the abdomen arise, with 

 broad triangular base, six divergent wings, which are nearly straight, and slightly fenestrated at 

 the base ; their conical distal ends do not reach the horizontal plane, in which the basal apex of 

 the abdomen lies. 



Dimensions. Length of the three joints, a 0'02, b 0'05, c 012 ; breadth, a 0'03, b 0'08, c 0'07. 



Habitat. Central Pacific, Station 266, depth 2750 fathoms. 



Genus 610. Theophcena, 1 Haeckel, 1881, Prodromus, p. 437. 



Definition. Theophsenida (vel Tricyrtida multiradiata clausa) with nine 

 lateral wings on the abdomen. 



The genus Theophcena, differs from the preceding six-radiate Hexalatractus in the 

 possession of nine lateral wings, and may be derived from the triradiate Rhopalocanium 

 by interpolation of six secondary wings between the three primary apophyses. 



1. TJieophcena corona, n. sp. (PI. 70, fig. 12). 



Shell rough, nearly spindle-shaped, with two sharp strictures. Length of the three joints = 

 4:9: 16, breadth = 5 : 12 : 10. Cephalis hemispherical, very thick-walled, with a conical horn of 



1 Theophcena, = Divine shell ; Ms, /fecinct. 



