1206 THE VOYAGE OF H.M.S. CHALLENGER. 



8. Lithomelissa thoracites, Haeckel. 



Litlwmelissa thoracites, Haeckel, 1862, Monogr. d. Radiol., p. 301, Taf. vi. figs. 2-8. 

 Lithomelissa tJwracites, R. Hertwig, 1879, Organism, d. Radiol., p. 76, Taf. viii. fig. 1. 



Shell smooth, with deep collar stricture. Cephalis ovate, with two divergent, slender, conical 

 horns, of about half the length ; a major oblique occipital horn on the posterior face, and a minor, 

 nearly horizontal horn above the collar stricture, on the anterior face. Thorax about as large as 

 the cephalis, truncate, ovate. Pores of both joints irregular, roundish, of different sizes. From the 

 upper half of the thorax, below the collar stricture, there arise three slender, conical divergent feet, 

 about as long as the cephalis. Mouth truncate, wide open, not constricted. On the numerous 

 varieties of this common species compare my Monograph, on the structure of the ovate central 

 capsule (enclosed in the cephalis), Hertwig, loc. cit. 



Dimensions. Cephalis 0/05 to 0'06 long, 0'04 to 0'05 broad ; thorax 0'03 to 0;05 long, 0'05 to 

 0-07 broad. 



Habitat. -Cosmopolitan ; Mediterranean, Atlantic, Indian, Pacific, surface. 



9. Lithomelissa mediterranea, J. Miiller. 



Lithomelissa mediterranea, J. Miiller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 45, Taf. vi. 



fig. 11. 

 Lithomelissa meJiterranea, Haeckel, 1862, Monogr. d. Radiol., p. 302. 



Shell smooth, with sharp collar stricture. Relative length of the two joints = 4:5, breadth = 4:5. 

 Cephalis campanulate, conical, with two divergent small conical horns, a major occipital subvertical 

 horn near the summit, and a minor sub-horizontal frontal horn near the collar stricture. Thorax 

 truncate, ovate, little larger than the cephalis. From its lower part there arise three short conical, 

 divergent feet, scarcely half as long as the cephalis (in Miiller's figure one of them is seen 

 shortened, opposite to the frontal horn). Pores irregular, roundish, much smaller in the cephalis 

 than in the thorax. Mouth wide open, not constricted. 



Dimensions. Cephalis 0'04 diameter, thorax O05 diameter. 



Habitat. Mediterranean (French shore), J. Miiller, surface. 



10. Lithomelissa bicornis, Ehrenberg. 



Lithomelissa bicornis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. ii. 

 fig. 7. 



Shell smooth, with deep collar stricture. Eelative length of the two joints = 1:3, breadth = 1:2. 

 Cephalis hemispherical, with two divergent, stout and straight, pyramidal horns ; a larger occipital 

 horn sub-vertical near the summit, and a smaller oblique frontal horn near the collar stricture. 

 Thorax subspherical, twice as large, with larger irregular, roundish pores. From its lower half there 

 arise three divergent curved pyramidal feet of about the same length. Mouth constricted, only one- 

 third as broad as the thorax. 



Dimensions. Cephalis 0'02 long, 0'03 broad ; thorax 0'06 diameter. 



Habitat. Atlantic, Stations 348 to 353, surface. 



