REPORT ON THE RADIOLARIA. 1509 



character. The anniUar constrictions of the multiartieulatc shell and the corresponding 

 internal annular septa are here not separated, and do not lie in parallel, transverse planes 

 (as usually happens), but they are all or partly connected in the form of an ascending spiral, 

 so that the joints are not perfectly separated. An' ii-regularity or asymmetry of growth 

 on the different sides of the shell is probably the cause of this strange, spiral structure. 



Subgenus 1. Spirocyrtidium, Haeckel. 



Definition. — Shell conical, gradually dilating towards the wide open terminal 

 mouth. 



1. Spirocyrtis scalaris, n. sp. (PI. 76, fig. 14). 



Shell conical, gradually dilating towards the wide open mouth, with ten to twelve spiral 

 convolutions, which correspond to the same number of short and broad chambers or joints, 

 gradually increasing in breadth ; all joints form together a spirally winding staircase. The length 

 or height of the single joints or stairs is about equal, and each bears four or five transverse rows of 

 small, square pores. Cephalis fiat, cap-shai3ed, with two or three short divergent horns. 



Dimensions. — Length of the shell (with ten joints or turnings) 0'16, length of each joint (on 

 an average) 0"016 ; breadth of the third joint 0'04, of the fifth joint 0'07, of the tenth joint 01. 



Habitat. — Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms. 



2. Spirocyrtis cornutella, u. sp. (PL 76, fig. 13). 



Shell conical, gradually dilating towards the wide mouth, similar to the preceding, but 

 differing in the curved axis, and the broader and shorter joints, each of which bears only two 

 or three transverse rows of square pores. The turnings of the staircase are not so sharp, nor 

 so distinct, as in the preceding species. Cephabs with a single short horn. 



Dimensions. — Length of the shell (with eight joints) 01 ; breadth of the fourth joint 0'05, of 

 the eighth joint O'OS. 



Habitat. — Central Pacific, Station 270, depth 2925 fathoms. 



Subgenus 2. Spirocyrtoma, Haeckel. 



Definition. — SheU ovate, or nearly spindle-shaped, more or less tapering towards the 

 narrower, somewhat constricted mouth. 



3. Spirocyrtis holospira, n. sp. (PL 76, fig. 16). 



Shell subovate, twice as long as broad, without external strictures, but with an internal regularly 

 descending spiral septum, which separates seven to nine broad joints of nearly equal lengths ; the 



