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



4. Lithoptera tetragona, n. sp. 



Four equatorial spines compressed, four-edged, with large latticed apophyses, each crossed by 

 four transverse beams, which are connected at regular distances by eight to twelve rods parallel to 

 the spine. (Therefore each wing with three rows of square meshes.) Wings placed in the equatorial 

 plane and grown together by their meeting lateral ends, forming a square equatorial girdle of 

 lattice-work. Sixteen smaller spines simple, thin, prismatic, without apophyses. 



Dimensions. Diameter of the square body 0'4 ; length of the inner square 0'22. 



Habitat. North Pacific, Station 244, surface. 



Subgenus 2. Lithopterella, Haeckel. 



Definition. Twelve spines (four equatorial and eight tropical) with transverse 

 apophyses ; the eight polar spines simple, without apophyses. 



5. Lithoptera quadrata, n. sp. (PI. 131, fig. 10). 



Twelve spines with transverse apophyses ; eight (polar) spines simple, small, without apophyses. 

 Four equatorial spines very large and stout, compressed, each crossed by four transverse beams, which 

 are connected by eight to ten rods parallel to the spine (therefore each wing with three rows of 

 irregular rectangular meshes). Wings placed in the equatorial plane and grown together by their 

 meeting lateral ends, forming a square equatorial girdle of lattice-work. Eight tropical spines 

 thin, crossed by a long and thin transverse beam, which bears on its distal side eight to ten rods 

 parallel to the spine. 



Dimensions. Diagonal of the square body 0'35 ; length of the inner square 0'18. 



Habitat. South Atlantic, Station 326, surface. 



6. Lithoptera dodecaptera, n. sp. 



Twelve spines with transverse apophyses ; eight (polar) spines simple, small, without apophyses. 

 Four equatorial spines very large, quadrangular ; each crossed by three transverse beams, which are 

 connected by ten to twelve rods parallel to the spine (therefore each wing with two rows of square 

 meshes). Wings placed as in Lithoptera mulleri. Eight tropical spines much thinner, crossed each 

 by two transverse beams, which are connected by six to eight rods parallel to the spine (therefore 

 each wing with one row of rectangular meshes). 



Dimensions. Diagonal of the square body O4 ; length of the inner square 0'25. 



Habitat. Central Pacific, Station 2 71, surf ace. 



Subgenus 3. Lithopteromma , Haeckel. 

 Definition. All twenty spines with transverse apophyses. 



