117(3 THE VOYAGE OF H.M.S. CHALLENGER. 



Subgenus 1. Acrocorona, Haeckel, 1881, Prodromus, p. 430. 

 Definition. — Feet simple, not l)ranclied nor forked. 



1. Calpophwna tetrarrhahda, n. sp. 



Shell subspherical, tuberculate, with subregular circular pores. Apical horn conical, about as 

 long as the sheU. Basal plate with a regular cross of four equal cortinar pores, separated by four 

 bars ; these are crossed in the sagittal and frontal diameter, and prolonged into four equal conical 

 divergent feet, about as long as the shell. 



Dimensions. — Shell O'l diameter, horn and feet O'l to 0'12 long. 



Habitat. — South Pacific, Station 297, depth 1775 fathoms. 



2. Calpophcena hexarrhabda, n. sp. (PL 53, figs. 17, 18). 



Shell subspherical, rough, with irregular roundish pores. Apical horn conical, shorter than the 

 shell. Basal plate (fig. 18) with three pairs of triangular pores, two larger (cardinal) pores in the 

 middle, two smaller (cervical) at the dorsal, and two intermediate (jugular) at the veutral side. 

 The bars between them are prolonged into six equal cylindrical divergent feet, nearly as long as the 

 shell, provided with a spiny knob at the end. 



Dimensions. — Shell 0'09 long, 0'08 broad ; horn and feet 0"0G to 0'08 long. 



Habitat. — Tropical Pacific, Station 224, depth 1850 fathoms. 



3. CalpopjluBiia ennearrhahda, n. sp. 



Shell subspherical, spiny, with irregular, roundish pores. Apical horn cylindrical, longer than 

 the shell. Basal i^late with nine collar pores, three larger central alternating with three pairs of 

 smaller peripheral (like PL 87, fig. 2). Corona with nine slender cylindrical, slightly curved, 

 divergent feet, somewhat longer than the shell. 



Dimensions. — Shell Oil long, O'l broad ; horn and feet 012 to 015 long. 



Habitat. — North Pacific, Station 241, depth 2300 fathoms. 



4. Ccdp)ophcena ennea2)hyUa, n. sp. 



Shell ovate, smooth, with regular circular pores. Apical horn pyramidal, half as long as the 

 shell. (Basal plate with four cortinar pores?) Corona with nine broad, lamellar, truncate, 

 vertical feet, about as long as the horn. 



Dimensions. — Shell 012 long, 0'09 broad; horn and feet 0'06 long. 



Habitat. — Central Pacific, Station 271, surface. 



