1156 THE VOYAGE OF H.M.S. CHALLENGER. 



prismatic, about as long as the shell cUameter, somewhat curved. The apical horn stands on the 

 apex, the frontal horn half-way up the shell. 



BimeTisions. — Shell 0-08 long, 0-06 broad; horns and feet 0-05 to 0-07 long. 



Habitat. — Central Pacific, Station 272, depth 2600 fathoms. 



3. Archipera hicornis, n, sp. 



Shell ovate, rough, with small regular circular, sparsely scattered pores. Basal plate with four 

 larger central and a peripheral coronal of twelve smaller pores. Two horns near the apex widely 

 divergent, somewhat shorter than the shell, of equal size and similar form. Three feet twice as. 

 long, horizontally expanded. All five spines slender, three-sided pyramidal, straight. 



Bimeiisions. — Shell 0'07 long, 0-06 broad ; horns O'Oo long, feet O'l long. 



Mahitat — Central Pacific, Station 271, depth 2425 fathoms. 



4. Archipera tricornis, n. sp. 



Shell subspherical, smooth, with subregular circular pores. Basal plate with four large meshes 

 (two major cardinal and two minor jugular pores). On the apex three divergent pyramidal horns 

 of different size, one larger occipital and two smaller frontal horns. Three feet prismatic, about' 

 twice as long as the shell. 



Dimensions. — Shell diameter 0'05, length of the feet 01. 



Habitat, — ^North Pacific, Station 253, depth 3125 fathoms. 



5. Archipera quadricornis,,Xi.. sj). 



Shell ovate, smooth, with a small number of irregular roundish, widely scattered pores; 

 Basal plate with four crossed meshes of nearly equal size. On the equator there arise four divergent 

 prismatic horns of nearly equal size, three of which correspond to the three feet, whilst the fourth is 

 opposite to the caudal foot. The three feet are also prismatic, as long as the shell, horizontally 

 expanded. (Similar to the upper half of Lithomdissa deoacantha, PI. 56, fig. 2, but without thorax.) 



Dimensions. — Shell 0-05 long, 0'04 broad ; horns and feet 0'06 long. 



Habitat. — South Pacific, Station 300, depth 1375 fathoms. 



6. Archipera multicornis, n. sp. 



SheU hemispherical, spuay, with irregular polygonal pores. Basal plate with six meshes (?). 

 Between the smaller spines of the surface arise six larger conical divergent horua Thi-ee feet also 

 conical, divergent, about twice as long as the sheU and the horns. 



Dimensions. — SheU 0-05 long, 0-07 broad ; horns 0-05 long, feet 01 long. 



Habitat. — Central Pacific, Station 274, depth 2750 fathoms. 



