1308 THE VOYAGE OF H.M.S. CHALLENGER. 



transverse rows of alternating square pores. Mouth little constricted, nearly as long as the thorax, 

 with a narrow, prominent peristome. 



Dimensions. Cephalis 0'02 long, 0'03 broad ; thorax 0'08 long, O05 broad. 



Habitat. Arctic Ocean, Greenland (Schaffner) ; Iceland (Krabbe). 



11. Dictyocephalus ampulla, n. sp. 



Shell thin- walled, smooth, with slight collar stricture. Length of the two joints = 1:4, 

 breadth = 1 : 3. Cephalis subspherical, without pores, hyaline. Thorax inflate, subspherical, 

 with scarce and small, widely-scattered, circular pores. Mouth constricted, only one-third as 

 broad as the thorax, with a narrow, prominent peristome. 



Dimensions. Cephalis 0'02 long, 0'02 broad ; thorax 0'08 long, 0'07 broad. 



Habitat. Western Tropical Pacific, Station 225, depth 4475 fathoms. 



Subgenus 2. Dictyocryphalus, Haeckel, 1881, Prodromus, p. 430. 



Definition. Mouth of the thorax flat or truncate, without prominent ring-like 

 peristome. 



12. Dictyocephalus obtusus, Ehrenberg. 



Dictyocephalus obtusus, Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 830. 

 Lophophcena obtusa, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 40. 



Cornutella obtusa, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 877. 

 Dictyocephalus obtusus, Haeckel, 1862, Monogr. d. Radiol., p. 296. 



Shell smooth, thick-walled, with distinct collar stricture. Length of the two joints = 5:6 

 breadth = 4:5. Cephalis ovate, little smaller than the subcylindrical thorax. Pores subregular, 

 circular, of little different sizes. Mouth truncate, without ring-like peristome. 



Dimensions. Cephalis 0'05 long, 0'04 broad ; thorax 0'06 long, O05 broad. 



Habitat. Fossil in Tertiary rocks of Sicily (Caltanisetta), Grotte, &c. 



13. Dictyocephalus globiceps, n. sp. (PL 62, fig. 7). 



Shell rough, thin-walled, with distinct collar stricture. Length of the two joints = 6:8, 

 breadth = 6:7. Cephalis subspherical, large, with circular, double-contoured pores. Thorax 

 cylindrical, with irregular, roundish pores, the size of which, like the thickness of the wall, 

 decreases gradually towards the truncate mouth, which has no ring-like peristome. 



Dimensions. Cephalis O06 long, 0'06 broad ; thorax, 0'08 long, 0'07 broad. 



Habitat. Central Pacific, Station 271, depth 2425 fathoms. 



