1652 THE VOYAGE OF H.M.S. CHALLENGER. 



16. Challengeria trigona, Haeckel. 



Ghallengeria macleari, var., John Murray, 1879, in littens, Narr. Chall. Exp., vol. i. p. 226, 

 pi. A, fig. 36. 



Shell triangular, with three rounded corners ; the two lateral sides nearly straight, equal, the 

 aboral side more or less convex and somewhat shorter. Peristome a curved half-tube (often longer 

 than in Murray's figure), one-third to one-half as long as the shell, with three short triangular 

 diverging and ascending teeth of equal length. 



Dimensions. Length of the shell 0'25 to 0'3, breadth 0'2 to 0'25; length of the peristome O08 

 to 012. 



Habitat. South Atlantic, Stations 332 to 335, depth 1425 to 2200 fathoms. 



17. Challengeria trifida, n. sp. 



Shell ovate, more or less compressed, about two-thirds as long as broad. Peristome semi- 

 tubular, obliquely ascending, about one-third as long as the shell, in the lower half simple, in the 

 upper trifid, with three curved divergent teeth ; the dorsal odd tooth shorter than the paired lateral 

 teeth. 



Dimensions. Length of the shell 0'3 to 0'36, breadth 0'24 to 0'28. 



Habitat. South Pacific, Station 289, depth 2550 fathoms. 



Subgenus 4. Challenger omma, Haeckel. 

 Definition. Peristome with four to six or more teeth. 



18. Challengeria quadridens, n. sp. 



Shell subglobose, with nearly circular perimeter. Peristome an oblique short and broad tube, 

 the breadth of which is twice as great as its length and equal to the radius of the shell. Margin 

 of the peristome with four divergent, short, triangular teeth, the two dorsal teeth half as long as the 

 two ventral. 



Dimensions. Diameter of the shell 0'22 to - 24, breadth of the peristome O'l. 



Habitat. Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms. 



19. Challengeria bromleyi, n. sp. (PL 99, fig. 3). 



Shell ovate, lenticular, strongly compressed. Peristome a broad, trapezoidal, horizontal lamella, 

 the breadth of which is twice as great as its length and nearly equal to the diameter of the shell ; 

 its margin with four divergent triangular lamellar teeth, the two dorsal teeth three times as long 

 as the two ventral. 



Dimensions. Length of the shell 0'08 to 01, breadth 0'05 to- 0'07 ; breadth of the peristome 

 0-08. 



Habitat. North Pacific, Stations 244 to 253, surface, and in various depths. 



