1384 THE VOYAGE OF H.M.S. CHALLENGER. 



10. Calocyclas gigas, Haeckel. 



Cycladophora gigas, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. 

 fig. 1. 



Shell with two sharp strictures. Length of the three joints = 2:5:3, breadth = 2:6:4. 

 Cephalis subspherical, rough, with a short and broad conical horn of half the length. Thorax 

 subspherical, campanulate, thorny, with subregular, circular pores (smaller and more numerous than 

 in the preceding). Abdomen cylindrical, smooth, with a small number of sparsely disposed, 

 roundish, irregularly scattered pores. Peristome with twenty to thirty short, lamellar, truncate, 

 vertical feet about half as long as the cephalis. 



Dimensions. Length of the three joints, a 0'06, b 015, c 0'09 ; breadth, a 0'06, I 018, c 012. 



Habitat. Fossil in Barbados. 



Subgenus 3. Calocycloma, Haeckel. 

 Definition. Thorax smooth ; abdomen spiny or thorny. 



11. Calocyclas casta, n. sp. (PL 73, fig. 10). 



Shell ovate, with two sharp strictures. Length of the three joints = 1:2:8, breadth = 2:4:8. 

 Cephalis hemispherical, with a strong pyramidal horn of twice the length. Thorax campanulate, 

 smooth, with small, regular, circular pores. Abdomen inflated, subspherical, covered with large 

 conical spines, and large intervening circular pores (four times as broad as the thoracic pores). 

 Mouth constricted, only one-third as broad as the abdomen, with a peristome of nine to twelve 

 conical vertical feet as long as the abdominal spines. (In the specimen figured they were broken off'.) 



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



Habitat. Central Pacific, Station 272, depth 2600 fathoms. 



12. Calocyclas pudica, n. sp. 



Shell ovate, with two distinct strictures. Length of the three joints =1:3:8, breadth = 1:4:6. 

 Cephalis subspherical, with a conical horn of three times the length. Thorax and abdomen nearly 

 of the same shape as in the preceding species, but more slender, and the regular, circular pores of 

 the abdomen only twice as broad as the thoracic pores. Conical spines of the abdomen only half 

 as large, but more numerous. Peristome constricted, half as broad as the abdomen, with sixteen to 

 twenty short, conical, vertical feet as long as the cephalis. 



Dimensions. Length of the three joints, a 0'02, b 0'06, c 016 ; breadth, a 0'025, b 0'08, c 012. 



Habitat. Central Pacific, Station 266, depth 2750 fathoms. 



Subgenus 4. Calocycloma, Haeckel. 

 Definition. Thorax and abdomen spiny or thorny. 



