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



as the shell. Spiral turnings simple, all nearly of the same breadth and scarcely broader than the 

 simple spherical medullary shell. 



Dimensions. — Length of the cortical shell (with six spiral convolutions) 0-15, breadth 013 ; 

 diameter of the medullary shell 0-012. 



Habitat. — Mediterranean, Messina, Haeckel, surface ; Atlantic, Stations 348 to 353, surface. 



2. Lithelius 2)rimordialis, E. Hertwig. 



Lithelius primordialis, E. Hertwig, 1879, Organism, d. Eadiol., p. 54, Taf. vi. figs. 4, 4a. 



Cortical shell subspherical, covered with numerous simple, bristle-shaped radial spines, longer 

 than the shell. Spiral turnings simple, with gi-adually increasing breadth, so that the beginning of 

 the third spiral is twice as broad as the first and as the simple spherical medullary shell. 



Dimensions. — Diameter of the cortical shell (with two spiral convolutions) 0'12 ; diameter of the 

 medullary shell 0'02. 



Habitat — Mediterranean, Messina, E. Hertwig, surface. 



3. Lithelius alveolina, Haeckel, 1862. 



Lithelius alveolina, Haeckel, 1862, Monogr. d. Radiol., p. 520, Taf. xxvii figs. 8, 9. 



Cortical sheU spherical, covered with simple, very numerous (two hundred to three hundred or 

 more), short, bristle-shaped radial spines, scarcely half as long as the radius of the shell. Spiral 

 turnings simple, with gradually increasing breadth, so that the beginning of the thu'd spiral is three 

 times as broad as the first and as the simple spherical medullary shell. 



Dimensions. — Diameter of the cortical shell (with four spiral convolutions) 0'2 ; diameter of the 

 medullary shell O^Ol. 



Habitat. — Cosmopolitan ; MediteiTanean, Atlantic, Pacific, on many Stations, surface. 



4. Lithelius capreolus, n. sp. 



Cortical shell lentelliptical, one and a fourth times as long as broad, covered with numerous (eighty 

 to one hundred and twenty or more) short, branched radial spines, about half as long as the radius 

 of the shell ; each spine once or twice dichotomous, with curved divergent branches. Spiral 

 turnings simple, with gradually increasing breadth, so that the beginning of the thiixl spiral is twice 

 as broad as the fii'st, and as the simple spherical medullary shell. 



Dimensions. — Length of the cortical shell (with four spiral convolutions) 018, breadth 014 ; 

 diameter of the medullary shell 0'015. 



Habitat. — Pacific, central area, Station 274, surface. 



Subgenus 2. Drymospira, Haeckel, 1881, Prodromus, p. 464. 

 Definition. — Spiral convolutions of the cortical shell double. 



