REPORT ON THE RADIOLARIA. 1663 



of marginal spines, and exhibits therefore the same relation to it that Challcngeron 

 bears to ChaUcngeria. Only two species have been observed ; the first of these bears, 

 besides the large mai-ginal spines, numerous flinty bristles on the surface of the shell. 



1. Porcupinia aculeata, n. sp. 



Shell ovate, one and one-third times as long as broad, shghtly compressed, covered with short, 

 bristle-shaped spines over the whole surface, simOar to Entocammla hirsuta (PI. 99, fig. 20). The 

 keeled margin is armed with numerous long and stout radial spines, which are alternately larger 

 and smaller, as in Chalkiujcron moseki/i (PI. 99, fig. 14) ; the larger about as long as the radius, the 

 smaller half as long. Peristome with two straight, parallel teeth. Pharnyx funnel-shaped, half 

 as long as the radius, its outer aperture twice as broad as the inner. 



Dimensions. — Length of the shell 0'24, breadth 0'18 ; peristome 0-05. 



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



2. Porcupinia cordiformis, n. sp. (PI. 99, fig. 16). 



Shell heart-shaped, nearly triangular, with a deep, concave bosom at the broad oral base, and a 

 bunch of five to nine divergent spines at the blunt aboral apex, the middle spine (in the main 

 axis) larger than the others. Peristome with two parallel, short, triangular teeth, which are 

 obliquely inclined over the mouth (their upper convex edge nearly horizontal). Pharynx cylindrical, 

 short, curved, and obliquely descending. 



Dimensions. — Diameter of the shell 0'2 to 0'25, of the pharynx 0-05 to 0'08. 



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



Family LXXIX. M ed us etti D A, n. fam. (Pis. 118-120). 



Definition. — Ph^eodaria with a simple, ovate, hemispherical or cap-shaped lattice- 

 shell of peculiar alveolate structure, and with hollow articulate feet surrounding the 

 widely open" mouth. Central capsule excentric, placed in the aboral half of the shell- 

 cavity. 



The family Medusettida represents a peculiar group of remarkable PHyEODARiA, 

 which are similar to the Challengerida and Tuscarorida in the general form of the 

 monaxonian shell and its apophyses, but difi"er from both families in the strange alveolate 

 structure of the shell and of the hollow articulate feet surrounding its mouth. All the 

 forms of this family here described are new, and not a single species was known before 

 the discoveries of the Challenger. The majority seem to be inhabitants of the deep- 

 sea, and occur mainly in those places where other families of Ph.^:odaria (Aula- 

 canthida, Aulosphajrida, Crelodendrida) are also well represented ; they are, however, 

 nowhere so common as these latter families. Their long feet and the small delicate 



