REPORT ON THE RADIOLARIA. 1329 



The genus Pterocanium differs from the preceding Theopodium in the fencstration of 

 the three terminal feet, which are basal prolongations of the three radial ribs, enclosed in 

 the wall of the thorax and the abdomen. Often also these ribs are partly or wholly 

 fenestrated. It corresponds to Lychnodictyum among the Dicyrtida, and may be 

 derived from this by development of an abdomen. The latter forms sometimes three 

 concave bays, at other times three convex lobes between the three latticed feet. 



Subgenus 1. Pterocanarium, Haeckel. 



Definition. Free basal edge of the abdomen between the three feet concave, forming 

 three shallower or deeper bays between them. 



1. Pterocanium proserpinoe, Ehrenberg. 



Pterocanium proserpince, Ehrenberg, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, 



p. 299, Taf. xi. fig. 22. 

 Pterocanium proserpince, Haeckel, 1862, Monogr. d. Radiol., p. 332. 



Shell campanulate, rough. Length of the three joints = 1:4:2, breadth 1:5:6. Cephalis 

 subspherical, with a triangular-pyramidal vertical horn of thrice the length. Thorax hemispherical, 

 without prominent swellings. Abdomen shorter, with three concave basal bays. Pores in the 

 thorax and abdomen nearly equal, subregular, circular. Feet from the girdle (or the lumbar 

 stricture) little divergent, nearly straight. 



Dimensions. Length of the three joints, a 0'02, b 0'08, c 0'04 ; breadth, O3, b 01, c 012. 



Habitat. Mediterranean, Candia, Spratt, depth 1100 fathoms. 



2. Pterocanium gravidum, n. sp., (PI. 73, fig. 3). 



Shell campanulate, nearly three-sided pyramidal, smooth. Length of the three joints = 1:4:3, 

 breadth = 1:6:10. Cephalis subspherical, with a pyramidal straight horn of twice the length, 

 Thorax hemispherical, without prominent swellings. Abdomen shorter, with three concave basal 

 bays ; its network prolonged to the ends of the feet. Pores in the thorax and abdomen of nearly 

 equal size, irregular, roundish. Feet from the girdle strongly divergent, with convex back. 



Dimensions. Length of the three joints, a 0'015, b 0'075, c 0'06 ; breadth, a 0'02, b 012, c 0'2. 



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



3. Pterocanium orcinum, n. sp. (PI. 73, ng. 2). 



Shell campanulate, nearly three-sided pyramidal, covered with conical spines. Length of the 

 three joints = 1:4:3, breadth = 1:5:6. Cephalis hemispherical, with a conical horn of the 

 same length. Thorax without prominent swellings, with subregular, circular pores. Abdomen 



(ZOOL. CHALL. EXP. PART XL. 1886.) Rr 167 



