1634 THE VOYAGE OF H.M.S. CHALLENGEE. 



2. Aulonia j^entagonia, ii. sp. 



Meshes subregular, pentagonal, intermingled with a smaller number of quadrangular and 

 triangular irregular meshes. Bars cylindrical, of equal breadth. 



Dimensions. — Diameter of the spherical shell 2"8 to 3'2, of the me.shes 0'15 to 0'2 ; breadth of 

 the bars 0-01. 



Halitat. — South Pacific, Stations 293 to 302, depth 1375 to 2270 fathoms. 



3. Aulonia hexagonia, n. sp. (PI. Ill, fig. 1). 



Meshes regular or subregular, hexagonal, often intermingled with a variable number of 

 pentagonal and heptagonal meshes. Bars cylindrical, of equal breadth. 



Dimensions. — Diameter of the spherical shell 2'5 to 3"3, of the meshes 015 to 0'25; lireadth of 

 the bars 0-012. 



Habitat. — Tropical Atlantic, Stations 347 to 349, surface. 



4. Aulonia metagonia, n. sp. 



Meshes subregularly alternating, larger octagonal and smaller tetragonal. The network of this 

 remarkable species has a striking similarity to the arrangement of the radial tubes in some species 

 of Sycon, figured in my Monograph of the Calcispongias (1872, Bd. iii., Taf Ix. fig. 12). 



Dimensions. — Diameter of the sphere 4'4, of the greater octagonal meshes 0"24 to 0'3, smaller 

 tetragonal 01 to 012 ; breadth of the bars 0'007. 



Habitat. — Indian Ocean, Cocos Islands (Eabbe), surface. 



5. Aulonia polygonia, u. sp. 



Meshes irregular, polygonal, variable in form and unequal in size ; the majority usually pentagonal 

 or hexagonal, but numerous intermingled meshes with three, four, seven, or eight sides. Very 

 variable in the size of the bars and the form of the meshes. 



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

 0-008 to 0-12. 



Habitat. — Cosmopolitan ; Atlantic, Indian, Pacific, surface. 



Geuus 689. Aulastrum,^ n. gen. 



Definition. — Au 1 os p h se ri da with polygonal meshes in the network, the 

 tangential tubes of which form a simple lattice-sphere. Radial tubes arise at its 

 nodal points. 



1 ^wZ(::s')'Ms = TuLular star ; «u?n{f, iSirTroii. 



