1400 THE VOYAGE OF H.M.S. CHALLENGER. 



2. TJieoconus CBgcBus, Haeckel. 



Eucyrtidium cegcaum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 31 ; 



Mikrogeol., 1854, Taf. xxxv. a, xix. a, fig. 5. 

 Eucyrtidium cegceum, Haeckel, 1862, Monogr. d. Eadiol., p. 329. 



Shell flatly bell-shaped, nearly conical. Length of the three joints = 2:5:3; breadth =1:7:8. 

 CephaUs ovate, with a stout, straight, pyramidal horn of the same length. Thorax flat, bell-shaped. 

 Abdomen with increasing breadth towards the wide truncated mouth. Pores in all three joints 

 nearly of the same shape, regular, circular, three times as broad as the bars. 



Divicnsions. — Length of the three joints, a 0'02, b 0'05, c O^OS ; breadth, a 0'016, b 0'07, c 0*08. 



Habitat. — Mediterranean (Coast of Greece and Sicily), surface. 



3. Tlieocomis zanguebaricus, Haeckel. 



Eucyrtidium zangueharicum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, 

 Taf. ix. fig. 22. 



Shell bell-shaped. Length of the three joints = 1:2:1, breadth = 1:3:4. Cephalis ovate, 

 with a straight, pyramidal horn of half the length. Thorax hemispherical, without collar stricture, 

 but with evident girdle stricture. Abdomen dilated towards the wide truncated mouth. Pores 

 regular, hexagonal, of nearly equal size and form, four to six times as broad as the thin Ijars. 



Dimensions. — Length of the three joints, a 003, b 0-06, c 0-03 ; breadth, a 0-024, b 0-09, c Oil. 



Habitat. — -Indian Ocean (off Zanzibar), PuUen, depth 2200 fathonLS. 



4. Tlieoconus campanulatiis, Haeckel. 



? Eucyrtidium campanulatum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 

 p. 241. 

 Eucyrtidium camj^anulatum, Haeckel, 1862, Monogr. d. Eadiol., p. 329. 



Shell beH-shaped, smooth. Length of the three joints = 2:3:7, breadth = 3 : 7 : 10. Cephalis 

 small, spherical, with a short, conical, oblique horn of the same length. Thorax hemispherical, with 

 an external girdle stricture, prolonged into the truncated, barrel-shaped abdomen, which is a little 

 constricted at the very wide mouth. Pores small and very numerous, regular, circular, twice to 

 three times as broad as the bars. 



Dimensions. — Length of the three joints, a 0'02, b 0'03, c 0'07 ; breadth, a O'Oo, b 0'07, c 01. 



Habitat — North Atlantic, Station 352, surface. 



5. Tlieoconus orthoconus, n. sp. 



Shell perfectly conical, smooth. Length of the three joints = 1:2:3, breadth = 1:2:4. 

 Cephalis hemispherical, with a strong, straight, conical horn of the same length. Thorax conical, 

 without external girdle stricture, prolonged into the truncated, conical abdomen, which is gradually 



