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. — Cephahs 0-02 long, 003 broad ; thorax O'CS long, 0-05 broad. 



Habitat. — Arctic Ocean, Greenland (Schaffher) ; Iceland (Krabbe). 



11. Dictyocephalus ampulla, n. sp. 



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

 breadth = 1 : 3. Cephahs subspherical, without pores, hyahne. Thorax inilate, subspherical, 

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

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



Dimensions. — Cephahs 0-02 long, 0-02 broad ; thorax O'DS 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. 



Didyocephalus obimiis, Ehi-enberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 830. 

 Lophoplimia ohtusa, 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. Eadiol., p. 296. 



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

 breadth = 4:5. Cephahs ovate, httle smaller than the subcylindrical thorax. Pores subregular, 

 circvdar, of httle different sizes. Mouth truncate, without ring-like peristome. 



Dimensions. — Cephahs O'Oo long, 0'04 broad ; thorax 0'06 long, 0'05 broad. 



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



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



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

 breadth = 6:7. Cephahs subspherical, large, with circidar, double-contoured pores. Thorax 

 cylindrical, with in'egular, roundish pores, the size of which, hke the thickness of the wall, 

 decreases gradually towards the truncate mouth, which has no ruig-hke peristome. 



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



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



