REPOKT ON THE RADIOLABIA. 1655 



6. Challengeron triodon, n. sp. 



Shell ovate, one and a half times as long as broad, not compressed, with a single short and stout 

 conical spine on the apical pole, shorter than half the radius. Peristome short and broad, collar- 

 shaped, nearly half as broad and one-third as long as the shell, with three divergent terminal teeth, 

 an odd dorsal and two paired lateral. 



Dimensions. Length of the shell 0'25 to '3, breadth 015 to 0'2 ; length and breadth of the 

 peristome 01. 



Habitat. North Pacific, Station 245, surface. 



Subgenus 2. Challenger ebium, Haeckel. 



Definition. Margin of the shell with two widely distant aboral spines, opposite 

 in the sagittal plane, a dorsal and a ventral. 



7. Challengeron balfouri, John Murray. 



Challengeria balfouri, John Murray, 1879, in litteris, Narr. Chall. Exp.,vol. i. p. 226, pi. A, fig. 10. 



Shell subcircular, lenticular, strongly compressed, with two short divergent spines on the apical 

 margin (a dorsal and a ventral). Peristome slender, semitubular, as long as the radius, vertical, in 

 the distal half forked, with two parallel teeth. 



Dimensions. Diameter of the shell 0'08 to 016, length of the peristome 0'04 to 0'08. 



Habitat. North Atlantic, Stations 353 to 354, Hebrides, surface. 



8. Challengeron golfense, n. sp. 



Shell ovate, lenticular, compressed, with two short divergent spines on the apical margin (a 

 dorsal and a ventral). Peristome slender, semitubular, half as long as the radius, with three 

 terminal teeth, two short, vertically ascending, paired teeth and a larger odd tooth, which is 

 inclined obliquely over the mouth. 



Dimensions. Diameter of the shell 015 to 0'2, peristome 0'05 to 0'07. 



Habitat. North Atlantic, Faroe Channel, Gulf Stream, surface and at various depths, John 

 Murray. 



9. Challengeron richardsii, n. sp. (PI. 99, fig. 8). 



Shell subcircular, lenticular, strongly compressed, with two stout, divergent, straight spines on 

 the aboral margin (a dorsal and a ventral) which reach the length of the radius. Peristome 

 slender, semitubular, slightly curved, about as long as the radius, with three short, divergent, 



