1464 THE VOYAGE OF H.M.S. CHALLENGER. 



twice as long as the first and the third, and armed with six divergent, stout, pyramidal, radial spines 

 or wmgs of the same length. Cephalis flat, cap-shaped, with an oblique pyramidal horn of twice 

 the length. Pores regular, circular, hexagonally framed. 



Dimensions. — Length of the shell (with four joints) OlS, breadth 0-12. Length of the single 

 joints, a 0-02, b 0-04, c 0-02, d 01. 



Babitat.—CentTsl Pacific, Station 265, depth 2900 fathoms. 



2. ArtoiDhcena senaria, n. sp. 



Shell pear-shaped, with five distinct strictures. Length of the four middle joints little different. 

 The fifth joint is the broadest. From the first stricture there arise six radial ribs, which at the 

 fourth are prominent as six short, conical, divergent spines. The last joint is inversely hemi- 

 spherical, twice as long as the preceding. Cephalis hemispherical, with a conical horn of the same 

 length. Pores regular, circular. 



Dimensions. — Length of the shell (with six joints) 014, breadth 0-09 ; of each joint 0-02, of the 

 last 0-04. 



Habitat. — Central Pacific, Station 273, depth 2350 fathoms. 



3. ArtophcBua hexalatr actus, n. sp. 



Shell spindle-shaped, with three sharp strictures, and six triangular, latticed, divergent wings, 

 which arise from the collar stricture and descend along the two middle joints. Their terminal 

 points fall into the same plane as the Imsal end of the fourth inversely conical joint. Length of 

 the four joints = 1:2:4:2. Cephalis hemispherical, with a conical horn of the same length. 

 (Similar to Thcophama hcxaptcra, PI. 68, fig. 13, but with three distinct internal annular septa, 

 corresponding to the three external strictures.) 



Dimensions. — Length of the shell (with four joints) 018, breadth 0-08. Length of the four 

 single joints, a 0-02, b OM, c 0-08, d 0-04. 



Habitat. — South Pacific (off Juan Fernandez), Station 300, depth 1375 fathoms. " 



4. Artophcena hexapodiscus, n. sp. 



Shell ovate, without external strictures, but with five internal annular septa. Length of the 

 six joints = 1:2:3:4:3:6. Cephalis hemispherical, with a stout conical horn of twice the 

 length. The last joint is the broadest, inversely hemispherical. From the fourth and fifth joints 

 arise six divergent ribs, which are prolonged over the fifth stricture into six triangular, divergent, 

 fenestrated feet, about as long as the last Joint. Pores in the upper half of the shell regxilar, 

 circular, in the lower half irregular, roundish. 



Dimensions. — Length of thfe shell (with six joints) 0-2, breadth 012. Length of the single 

 joints, a O'Olo, b 0-025, c 0-03, d 004, c 003,/0-06. 



Habitat. — Western Tropical Pacific, Station 225, depth 4475 fathoms. 



