1388 THE VOYAGE OF H.M.S. CHALLENGER. 



Subgenus 2. Clathrocydoma, Haeckel. 



Definition. — Shell flatly conical, often widely campanulate, or nearly discoidal. 

 Ceplialis commonly with two or more horns 



7. Clathrocyclas alcmen(e, n. sp. (PL 59, fig. 6). 



Shell conical, with two indistinct strictures. Length of the three joints = 2 : 10 : 1, breadth = 

 2:12: 14. CeiDhalis hemis23herical, with two divergent, pyramidal horns ; frontal horn as long as 

 the cephalis, occipital horn of twice the length. Thorax conical, with large hexagonal meshes, 

 increasing gradually in size towards the short abdomen, which is represented only by a single 

 circular girdle of small, square, abdominal pores. Coronal of the peristome with twenty to thirty 

 triangular, divergent, nearly horizontal feet, as long as the cephalis. 



DimensioTis. — Length of the three joints, a 0'02, h 01, c O'Ol ; breadth, a 0'02, h 0'12, c 0"14. 



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



8. Clathrocyclas europce, n. sp. (PI. 59, figs. 11, 12). 



Shell conical, almost of the same form as the preceding nearly allied species, differing from it 

 in the concave (not straight) outline of the flatter conical thorax, in the more rounded form of its 

 pores, and in the subspherical form of the cephalis, bearing only a single conical horn of the 

 same length. Length of the three joints = 2:8: 1, breadth = 2 : 12 : 14. In fig. 11 the cephalis 

 is broken off, so that the four eortinar pores are visible (two smaller jugular and two larger cardinal 

 pores, separated by two coracal beams). 



Dimensions. — Length of the three joints, a 0-02, I O'OS, c O'Ol ; breadth, a 0-02, h 012, c 014. 



Habitat. — Mediterranean, Corfu (Haeckel), surface. 



9. Clathrocyclas semeles, n. sp. (PI. 58, fig. 5). 



Shell conical-campanulate, with two distinct strictures. Length of the three joints = 2 : 8 : 1, 

 breadth = 2 : 8 : 10. Cephalis hemispherical, with three divergent, conical horns (the caudal horn, 

 directed downwards, much longer than the occipital and fi-ontal horns). Pores of the thorax large, 

 roundish. Abdomen (as in the two preceding species) with only a single circle of forty to fifty 

 small square pores. Coronal with about the same number of short, triangular, almost horizontally 

 divergent feet. 



Bimensions. — Length of the three joints, a 0-02, h O'OS, c 0-01; breadth, a 0-02, h O'OS, c 01. 



Habitat. — Central Pacific, Station 271, surface. 



10. Clathrocyclas danaiis, n. sp. (PI. 59, figs. 13, 14). 



Shell flatly conical, with straight outline (as in Clathrocyclas alcmcncv, PI. 59, fa'g. 6). Length of 

 the three joints = 1:5:1, breadth = 2:8:1. Cephalis hemispherical, with a single, short, conical. 



