1026 THE VOYAGE OF H.M.S. CHALLENGER. 



2. Tripospyris cortiniscus, n. sp. (PL 84, fig. 6). 



Shell ovate, smooth, one and a third times as long as broad, with sharp ovate sagittal stricture 

 and broad primary ring. Basal plate with two large cardinal pores only. Occipital plate with two 

 pairs of very large pores ; facial plate and lateral sides with numerous smaller irregular rounchsh 

 pores. Apical horn small, conical, curved, half as long as the three basal feet, which are club- 

 shaped and three-edged, with thinner bases and half as long as the shell, strongly divergent. 



Dimensions. — Shell 012 long, 0-09 broad ; horn 0-03 long, feet 006 long. 



Habitat. — Central Pacific, Station 266, depth 2750 fathoms. 



3. Tripospyris semantis, n. sp. (PL 84, figs. 2, 3). 



Shell subspherical, smooth, somewhat broader than long, with slight sagittal stricture and sub- 

 circular parietal primary ring. Basal plate with two large semicircular cardinal pores. Facial and 

 occipital plate each with two pairs of large annidar pores and an odd large subapical pore ; lateral 

 sides with very numerous small roundish pores. Apical horn and caudal foot club-shaped, half as 

 long as the shell, angular, simple ; the two pectoral feet somewhat longer, nearly vertical, and at 

 the distal end with a small incision, nearly forked. 



Dimensions. — Shell 01 long, 012 broad ; horn and feet 0'05 to 0'07 long. 



Habitat. — North Pacific, Station 24-i, depth 2900 fathoms. 



4. Tnpospyris diomma, n. sp. (PL 84, fig. 5). 



Shell thorax-shaped, smooth, twice as broad as long, with deep sagittal stricture, two vaulted 

 ovate bosoms and smaller ovate internal primary ring. Basal plate with two large ovate cardinal 

 pores. Facial plate with three pairs, occipital plate with four pairs of large annular pores ; the 

 other lattice-work loose, with small and numerous irregular polygonal pores. Apical horn and 

 caudal feet slender and thin, curved, shorter than half the shell ; two pectoral feet also small, widely 

 divergent, more or less curved, deeply forked. 



Dimensions. — Shell 01 long, 016 broad ; horn and feet 0*2 to 0"25 long. 



Habitat. — South Atlantic, Station 332, depth 2200 fathoms. 



Subgenus 2. Tripospyrella, HaeckeL 



Definition. — Basal plate with three large collar pores (two paired posterior cardinal 

 pores, and an odd anterior sternal pore). 



5. Tripospyris triomma, HaeckeL 



Ceratospyris triomma, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xxi. 

 fig. 3. 



Shell subspherical, tuberculate, with slight sagittal stricture and circular internal ring. Basal 

 plate with three large pores, which are sometimes (but not in every specimen) surrounded by a 



