REPORT ON THE RADIOLARIA. 1367 



The genus Theophormis commences the series of the Theophormida, or the multi- 

 radiate Podocyrtida, as their oldest and simplest form. The three-jointed shell is flat, 

 campanulate or hat-shaped, and pierced by four or more radial ribs, four of which are 

 primary or perradial, the others secondary or interradial. Theophormis may be derived 

 from the similar Sethophormis by development of a lumbar constriction, and a third 

 joint or abdomen. 



1. Theophormis callipilium, n. sp. (PI. 70, figs. 13). 



Shell flat, hat-shaped, with two sharp annular strictures. Cephalis large, flatly cap-shaped, with 

 small, irregular, square meshes (fig. 3). The collar septum (fig. 2) is composed (as in the following 

 species) of four crossed, thin, horizontal beams, each of which is inserted at the collar stricture by 

 a three forked branch. From the centre of the collar stricture (in the common nodal point of the 

 four beams) there arises a vertical, axial rod, which is inserted at the flat top of the cephalis by five 

 branches (one central and four lateral). Length of the three joints = 1:3:2, breadth = 2:6:11. 

 Thorax flat, campanulate, with four primary perradial ribs (prolongations of the four cortinar beams), 

 and numerous (twenty to thirty) interpolated secondary ribs ; four of these are interradial (mid- 

 way between the four primary ribs), and bisect the four large, semicircular, perradial meshes at the 

 base of the thorax. Network of the thorax and abdomen subregular, with hexagonal meshes and 

 thin bars. Abdomen flatly expanded, somewhat curved, like the brim of a hat, half as broad in 

 the anterior (frontal) part as in the posterior (occipital) part, which is about as broad as the radius 

 of the thorax. The twenty to thirty radial ribs of the abdomen are prolongations of the thoracic 

 ribs, and are somewhat prominent at the margin of the peristome, which appears therefore elegantly 

 indented. 



Dimensions. Length of the three joints, a O02 to 0'03, b 0'06 to 008, c 0'03 to 0'06 ; breadth, 

 a 0-05 to 0-08, b O2 to 0'3, c 04 to 0'5. 



Habitat. Central Pacific, Station 271, surface. 



2. Theophormis medusa, n. sp. 



Shell flatly campanulate, with two distinct, annular strictures. Length of the three joints = 

 1:2:1, breadth = 2:5:8. Cephalis large, hemispherical. Thorax flatly conical, with four crossed 

 ribs, opposite in pairs in two meridional planes, perpendicular one to another, and prolonged into the 

 flat, nearly discoidal abdomen, which is half as broad as the thorax. The wall of the abdomen is 

 pierced by eight radial ribs ; four secondary ribs being interpolated between the four primary. Net- 

 work of the entire shell very delicate, with regular, hexagonal meshes, and very thin bars. Peristome 

 circular, not dentate. 



Dimensions. Length of the three joints, a 0'03, b 0'07, c 0'04 ; breadth, a 0'06, b 016, c 0'24. 



Habitat. Central Pacific, Station 266, surface. 



3. Theophonnis cruciata, n. sp. 



Shell flat, campanulate, with two distinct annular strictures. Cephalis flat, cap-shaped, with 

 irregular, square meshes. Thorax flat, conical, with hexagonal meshes. Abdomen flatly expanded, 



