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



beams in the principal axes, as in Octopylc). One wing of the sagittal girdle turns around the other 

 in two to three simple spiral turns. 



Dimensions. Length of the cortical shell 0'27, breadth O18 ; length of the medullary shell 0'04, 

 breadth 0'03. 



Habitat. South Pacific, Station 288, surface. 



3. Tholospira dendrophora, n. sp. (PI. 49, fig. G). 



Cortical shell covered with numerous (forty to fifty or more) branched radial spines, about half as 

 long as the shell; each spine with two to six dichotomous branches. Perimeter of the lateral plane 

 elliptical, one and a third times as long as broad. Eight internal egg-shaped gates, as in the 

 foregoing species. One single wing of the sagittal girdle turns around the other in three to four 

 spiral turns. 



Dimensions. Length of the cortical shell 0'22, breadth 017 ; length of the medullary shell - 05, 

 breadth 0'04. 



Habitat. Pacific, central area, Station 272, depth 2600 fathoms. 



Subgenus 2. Tholospironium, Haeckel. 



Definition. Spiral convolutions of the cortical shell double ; both wings of the 

 sagittal girdle turning around the transverse axis. 



4. Tfiolospira hystrix, n. sp. 



Cortical shell covered with numerous (sixty to eighty or more) simple conical spines, about 

 half as long as the shell Perimeter of the lateral plane hexagonal, one and a half times as long as 

 broad. Four internal kidney-shaped gates, as in Tetrapyle. Both wings of the sagittal girdle turn 

 round one another in two to two and a half double spiral turns. 



Dimensions. Length of the cortical shell 0'21, breadth 0'14 ; length of the medullary shell 0'04, 

 breadth 0-03. 



Habitat. North Atlantic, Station 354, surface. 



5. Tholospira cervicornis, n. sp. (PL 49, fig. 5). 



Cortical shell covered with numerous (forty to fifty or more) branched radial spines; each 

 spine antler-shaped, about as long as the medullary Larnacilla-shell, with eight to twelve 

 dichotomous branches (similar to Cromyodrymus abietinus, PI. 30, fig. 6). Perimeter of the 

 lateral plane elliptical, one and a third times as long as broad. Four internal kidney-shaped gates, 

 as in Tetrapyle. Both wings of the sagittal girdle turn round one another in one and a half to 

 two double spiral turns. 



Dimensions. Length of the cortical shell 0'2, breadtli 0'15 ; length of the medullary shell 

 breadth 0-025. 



Habitat. Pacific, central area, Station 271, depth 2425 fathoms. 



