1636 THE VOYAGE OF H.M.S. CHALLENGER. 



5. Aulastrum trichoceros, u. sp. 



Eadial tubes slender, straight, cylindro-conical, about twice as long as the smooth tangential 

 tubes, armed with six to eight verticils of lateral branches, each of which is composed of three 

 short curved branches (similar to those of Aulophacus lenticular is, PI. Ill, fig. 5rt). Meshes irregularly 

 polygonal, the majority tetragonal, intermingled with pentagonal and triangular meshes. 



Dimensions. — Diameter of the sphere 2'2 ; tangential tubes 0'12 long, 0'007 broad. 



Habitat. — South Pacific, Station 289, depth 2550 fathoms. 



6. Aulastrum tetraceros, n. sp. 



Eadial tubes straight, cylindrical, about three times as long as the smooth tangential meshes, 

 armed with three to six subregular cruciate verticUs of branches, each of which is composed of four 

 short, regularly crossed branches, bearing at the end a spinulate knob (similar to those of 

 Aulatractus fusiformis, PI. Ill, fig. 65). Meshes subregidar, square, intermingled with single 

 pentagonal and hexagonal meshes. 



Dimsnsions. — Diameter of the sphere 1"5, of the meshes 012 to 0'16 ; breadth of the bars 

 O'OOS. 



Habitat. — South Atlantic, Station 318, depth 2040 fathoms. 



7. Aulastrum pentaceros, n. &]). 



Eadial tubes straight, cylindrical, smooth, about as long as the smooth tangential tubes, armed 

 at the distal end with a corona of five curved teeth (of the same shape as in Cannosphccra 

 atlantiea, PI. 112, fig. 6). Meshes subregular pentagonal (intermingled with single tetragonal, 

 hexagonal, and heptagonal meshes). 



Dimensions. — Diameter of the sphere 5'0, of the meshes 0"2 ; breadth of the bars O^Olo. 



Habitat. — Indian Ocean, Madagascar (Eabbe), surface. 



8. Aulastrum 2^olyceros, n. sp. 



Eadial tubes spindle-shaped, tapering from the broader middle towards both ends, spiny, twice 

 as long as the spiny tangential tubes, armed at the distal end with a corona of twelve to twenty 

 divergent curved teeth (similar to the radial tubes of Auloscena tentorium, PI. 110, fig. 6). 

 Meshes irregular, polygonal, very variable in size and form. All tubes of this species are armed with 

 scattered, short, conical spines. 



Dimensions. — Diameter of the sphere 4-5, of the meshes 01 to 0-2 ; breadth of the bars 0'006. 



Habitat. — Central Pacific, Station 271, depth 2425 fathoms. 



