1402 THE VOYAGE OF H.M.S. CHALLENGER. 



9. Theoeonus ampullaceus, HaeckeL 



Lithocampe ampullacea, Ehrenberg, 1875, Abhandl, d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iv. 



fig. 1. 

 Theocorys ampullacea, Haeckel, 1881, Prodromus, p. 434. 



Shell bell-shaped, nearly conical, thorny. Length of the three joints = 3 :4 : 10 ; breadth = 

 4:8:15. Cephalis subspherical, with a stout lateral horn of the same length. Thorax hemi- 

 spherical, rough. Abdomen subspherical, widely truncated at both poles, spiny. Pores regular, 

 circular, three to four times as broad in the thick-walled abdomen as in the thin-walled thorax. 

 (Differs from the similar preceding species in the smaller horn and the two deeper strictures of the 

 shell.) 



Dimensions. Length of the three joints, a 0'03, b O04, c 01 ; breadth, a 0'04, b 0'08, c 015. 



Habitat. Fossil in Barbados. 



10. Theoeonus amplus, Haeckel. 



1, Podocyriis ampla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wisa. Berlin, p. 80, Taf. xvi. fig, 7. 

 1 Podocyrtis ampla, Biitschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxiii. fig. 16. 

 '\Eucyrtidium arnplum, Ehrenberg, 1873, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 248. 



Shell conical, smooth, with two broad internal annular septa. Length of the three joints = 

 1:3:4, breadth =1:4:5, Cephalis subspherical, with a very large, straight, conical horn of the same 

 breadth, which is as long as the conical thorax. Pores regular, circular, twice as broad in the 

 truncate, gradually dilated abdomen as in the thorax. 



Dimensions. Length of the three joints, a 0'03, b 0'09, c 012 ; breadth, a 0'03, b 012, e 015. 



Habitat. Fossil in Barbados. 



1 1 . Theoeonus ariadnes, n. sp. 



Shell conical, nearly bell-shaped, smooth. Length of the three joints = I ' 2 : 3, breadth = 1:3:5. 

 Cephalis subspherical, with a conical spine of about the same length. Thorax hemispherical, thiii- 

 walled. Abdomen conical, slightly constricted at the wide open mouth. Pores regular, circular, 

 twice as large in the thick-walled abdomen as in the thin-walled thorax. 



Dimensions. Length of the three joints, a 0-018 to 0'022, b 0'03 to 0'035, c O'OG to O'O 1 ? ; 

 breadth, a Q'015 to 0'02, b 0'04 to 0'06, c 0'07 to 0'09. 



Habitat. Cosmopolitan ; Atlantic, Indian, and Pacific Oceans, common, surface. 



12. Theoeonus dionysius, Haeckel. 



Thyrsocyrtis dionysia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. 



fig. 6. 



Thyrsocyrtis jacchia, , Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. 

 fig. 7. 



Shell bell-shaped, smooth. Length of the three joints = 1:3:5, breadth = 1:4:5. Cephalis 

 subspherical, with a conical, irregularly denticulate horn of twice or thrice the length. Thorax 



