1382 THE VOYAGE OF H.M.S. CHALLENGEK. 



shell. Thorax subspherical. Abdomen nearly cylindrical, little contracted towards the peristome. 

 Pores regular, circular, twice as broad in the thorax as in the abdomen, where they are separated by 

 slight longitudinal ribs. Corona of the peristome composed of sixteen to twenty-four vertical, 

 lamellar feet, which are longer than the abdomen, rectangular, and truncate at the end. 



Dimensions. — Length of the three joints, a 0'04, i O'OS, c 0'05 ; breadth, a O^OS, b O'll, c 0'09. 



Habitat. — Central Pacific, Station 225, depth 4475 fathoms. 



3. Calocyclas minervce, n. sp. 



Shell smooth, with two deep strictures, similar to Cydadoplwra stiligcra. Length of the three 

 Joints = 1:4:3, breadth = 1:4:3. CephaUs subspherical, with a large, conical horn of three times 

 the length. Thorax subspherical, with small, regular, circular pores. Abdomen cylindrical, with 

 truncate mouth and few irregular pores of different sizes, commonly arranged in three or four 

 subregular, transverse rows, with large intervening distances. Peristome with a corona of twelve 

 to twenty vertical, lamellar feet, which are about as long as the abdomen, and truncate at the end 

 (in Ehrenberg's figure these are broken off). 



Dimensions.— LQwgth. of the three joints, « 0-02, h 0-08, c 0-06 ; breadth, a 0-02, h 0-09, c 0-07. 



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



4. Calocyclas aniicce, n. sp. (PL 74, fig. 2). 



Shell smooth, with two slight strictures. Length of the three joints = 2:4:5, breadth = 2:5:5. 

 Cephalis subspherical, with a pyramidal horn of the same length. Thorax campanulate-conical ; 

 abdomen nearly cylindrical ; both with small, subregular, circular pores. Peristome with a corona 

 of twelve to fifteen small, triangular feet, only as large as the thickness of the shell-wall, and 

 separated by distances of twice the size. 



Dimensions. — Length of the three joints, a 0'04, h 0'08, c 01 ; breadth, a 0"04, b O'l, c 0"1. 



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



5. Calocyclas sacerdotis, n. sp. 



Shell smooth, with two deep strictures. Length of the three joints = 1:3:4, breadth = 1:3:3. 

 Cephalis ovate, with a pyramidal horn of three times the length. Thorax campanulate, conical ; 

 abdomen twice the length, cylindrical ; both with small, regular, circular pores. Peristome somewhat 

 constricted, with a corona of nine to twelve conical feet, which are as long as the cephalis, and 

 with the ends curved inwards, protecting the mouth. 



Dimensions. — Length of the three joints, a 0-03, b O'OS, c 012 ; breadth, a 0-03, h 0-09, c 0-09. 



Habitat. — Tropical Atlantic, Station 347, depth 2250 fathoms. 



6. Calocyclas vestalis, n. sp. (PL 74, fig. 3). 



Shell smooth, with two deep strictures. Length of the three joints = 1:2:3, breadth = 1:3:3. 

 Cephalis subspherical, with a pyramidal horn of twice the length. Thorax campanulate ; abdomen 



