REPORT ON THE RADIOLARIA. 1705 



usually irregularly ovate or triangular ; their outer aperture is armed with spines or 

 bristles, which are commonly larger than in the other parts of the apophyses. 



The mouth of the shell varies in form, according to the number and arrangement 

 of the teeth on its corners. It is therefore a narrow transverse fissure, with two broad 

 opposite lips and two corners, in the bidental forms (PL 100, figs. 5, 7), triangular in 

 the tridental species (figs. 14), quadrangular or square in the quadridental species, 

 Tuscarora belknapii (Narr. Chall. Exp., loc. cit., pi. A, fig. 15). The singular genus 

 Tuscaridium (fig. 8) exhibits four teeth, which are nearly horizontally divergent in 

 two pairs, a dorsal and a ventral pair (corresponding in position to the four feet of 

 Tuscarusa, fig. 7) ; the mouth is here prolonged into a cylindrical, spinulate proboscis, 

 which is curved towards the ventral face of the shell (fig. 8). 



The central capsule of the Tuscarorida is kidney-shaped or spheroidal, scarcely half 

 as large as the dark olive-green phseodium, which surrounds its anterior (oral) face. 

 Usually the capsule and the phseodium together fill up the aboral half of the shell- 

 cavity, and are separated from its walls by the calymma. The latter is pierced by 

 numerous branched and reticulately anastomosing pseudopodia, which arise from the 

 matrix enveloping the capsule, and pass over into a thin layer of sarcode, adjacent to 

 the inner surface of the shell. The astropyle or the main-opening of the central 

 capsule exhibits the usual radiate operculum and tubular proboscis of. the PH^EODARIA 

 (PL 115, fig. 3), and is directed towards the mouth of the shell. The number of the 

 parapylse or accessory openings seems to be variable in this family, and to correspond 

 to the number of radial feet which arise from the shell. Therefore Tuscaridium 

 possesses only one parapyle, which is diametrically opposite to the mouth, lies on the 

 aboral pole of the capsule, and is directed towards the single caudal tube. Tuscarora 

 seems to have three parapylse, corresponding to the three radial feet, and Tuscarusa 

 probably has four parapylse, directed towards its four radial feet; in the latter genus, 

 however, the capsule was not observed (the shell being empty) ; and in the other 

 Tuscarorida this important and difficult anatomical question must be solved by further 

 accurate examinations. 



The nucleus is nearly half as large as the central capsule, ellipsoidal, and contains 

 numerous nucleoli. In one specimen of Tuscarora belknapii I observed two nuclei 

 in the central capsule, and in another specimen of the same species John Murray 

 observed two central capsules (figured by him in the Narr. Chall. Exp., vol. i. pi. A, 

 fig. 15). 



Synopsis of the Genera of Tuscarorida. 



Three equidistant aboral radial feet, . . . . . .717. Tuscarora. 



Four equidistant aboral radial feet, .... . . 718. Tuscarusa. 



One single aboral foot or terminal spine, . . . . .719. Tuscaridium. 



(ZOOL. CHALL. EXP. PART XL. 1886.) Rr 214 



