REPORT ON THE RADIOLARIA. 1299 



The genus Sethocyrtis and the three following nearly allied genera differ from the 

 three preceding genera of Sethocorida in the form of the thorax, which is not gradually 

 dilated, conical, but cylindrical or ovate, with more or less constricted mouth. 

 ♦Sc^/iocj/j-i/s may be derived from Anthocyrtis by loss of the terminal feet. Its mouth 

 is quite simple, without tubular or annular peristome. 



1. Sethocyrtis oxycephalis, n. sp. {PL 62, fig. 9). 



Shell rough, subcouical, with slight collar stricture. Length of the -two joints = 4:9, breadth = 

 3 : 8. Cephalis ovate, with a pyramidal horn of half the length. Thorax campanulate, with regular, 

 circiilar pores, twice as broad as those of the cephaUs. Mouth constricted, scarcely half as broad 

 as the thorax. 



Dimensions. — Cephalis 0'04 long, 0'03 broad ; thorax 0-09 long, O'OS broad. 



Habitat. — Central Pacific, Stations 263 to 274, depth 2350 to 3000 fathoms. 



2. Sethocyrtis cancrina, Haeckel. 



Eucyrtidium cancrinum, Ehrenberg, 1875, Abliandl. J. k, Akad. d. Wiss. Berlin, p. 70, Taf. x. 



fig. 4. 



Shell smooth, bottle-shaped, with obliterated coUar stricture. Length of the two joints = 4 : 9, 

 breadth = 2 : 7. Cephalis subcylindrical, with a stout conical horn of the same length, and some- 

 times a smaller accessory horn at its base. Thorax ovate, truncate, with regular, circular, quin- 

 cuncial pores, twice as broad as those of the cephalis. Moutli little constricted, flat, nearly as broad 

 as the thorax. 



Dimensions. — Cephalis 0-04 long, 0'02 broad ; thorax 0"09 long, 0'07 broad. 



Habitat. — Fossil in Barbados. 



3. Sethocyrtis diomedis, n. sp. 



Shell thorny, pear-shaped, with slight collar stricture. Length of the two joints =: 3 : 16, breadth 

 = 4:20. Cephalis hemispherical, with a conical horn of twice the length. Thorax inflate, ovate, 

 truncate at both poles, with regular, circular pores, twice as broad as those of the thorax. Mouth 

 constricted, flat, half as broad as the thorax. 



Dimensions. — Cephalis 0-03 long, 0'04 broad ; thorax 012 to 016 long, 016 to 0'2 broad. 



Habitat. — Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms ; also fossil in 

 Barbados. 



4. Sethocyrtis menelai, n. sp. 



Shell spiny, pear-shaped, with sharp collar stricture. Length of the two joints = 3:15, breadth = 

 4 : 18. Cephalis subspherical, with a large, cylindro-conical horn, about as long as the whole shell. 



