1262 THE VOYAGE OF H.M.S. CHALLENGER. 



Subgenus 1. Acanthocorallium, Haeckel. 



Definition. Thorax with six divergent ribs or radial beams (three primary or perradial 

 alternating with three secondary or interradial). 



1. Acanthocorys hexapodia, n. sp. 



Cephalis large, ovate, with subregular hexagonal pores, and six strong, conical, simple, divergent 

 horns of the same length. Thorax flat, conical, smooth, with six large triangular basal holes, sepa- 

 rated by six strong, prismatic, smooth beams, which are connected only near the distal end by a 

 hexagonal ring of delicate, irregular network. "Collar septum with three meshes, separated by the 

 three centripetal prolongations of the three primary ribs. 



Dimensions. Cephalis 0'05 long, 0'04 broad ; thorax 0'12 long, O24 broad. 



Habitat. Central Pacific, Station 274, depth 2750 fathoms. 



2. Acanthocorys pristipodia, n. sp. 



Cephalis large, hemispherical, with irregular, polygonal pores, and numerous (ten to twenty) bristle- 

 shaped, radiating horns, which are conical at the base, and twice as long. Thorax flatly campanulate, 

 thorny, with six strong, serrate or spinulate, divergent, radial ribs, prolonged into six free conical 

 feet of the same length. Meshes of the thorax irregular, polygonal, a corona of six larger ones at 

 the base. Collar septum with four meshes, shaped as in PI. 56, fig. 6. 



Dimensions. Cephalis 0'04 long, 0'06 broad ; thorax O08 long, 018 broad. 



Habitat. North Pacific, Station 244, depth 2900 fathoms. 



3. Acanthocorys macropodia, n. sp. 



Cephalis small, subspherical, with irregular, roundish pores and numerous small, bristle-shaped 

 horns. Length of the two joints = 1:2, breadth = 1:6. Thorax sexangular, pyramidal, with six 

 very long and straight, widely divergent feet, which are prismatic and spiny, and three to five times 

 as long as the breadth of the shell. Only the upper third of the six ribs is connected by irregular, 

 roundish network, with six large triangular holes at the base. Collar septum with four meshes 

 which have the same relation to the six ribs as in Sethophormis hescalactis (PI. 56, fig. 6). 



Dimensions. Cephalis 0'025 diameter, thorax 0'05 long, 0'15 broad. 



Habitat. Central Pacific, Station 271, surface. 



4. Acanthocorys btitschlii, Haeckel. 



? Clathrocanium ehrenbergii, Biitschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvL pp. 514, 539, 

 Taf. xxxii. fig. 18, a, b. 



Cephalis large, subspherical, with numerous small, circular pores and three to six divergent, 

 slender, apical horns. Thorax flatly conical, smooth, not much larger than the cephalis, with six 



