FORAMINIFERA AND RADIOLARIA. 



79 



type, distinguished by the whiteness of its 'test,' to which the Author 

 has given the name of Pilulina, from its resemblance to a homoeopathic 

 * globule' (Fig. 319,* d, e). The form of this is a very regular sphere; 

 and its orifice, instead of being circular and surrounded by a neck, is a 

 slit or fissure with slightly raised lips, and having a somewhat S-shaped 

 curvature. It is by the structure of its 'test,' however, that it is espe- 

 cially distinguished; for this is composed of the finest ends of sponge- 

 spicules, very regularly 'laid' so as to form a kind of felt, through the 

 substance of which very fine sand-grains are dispersed. This 'felt' is 

 somewhat flexible, and its components do not seem to be united by any 

 kind of cement, as it is not affected by being boiled in strong nitric acid; 

 its tenacity, therefore, seems entirely due to the wonderful manner in 

 which the separate siliceous fibres are ' laid.' It is not a little curious that 



Fia. 319* 



Arenaceous Foraminifera: a, Saccamina spherica; 6, the same laid open; e, portion of the test 

 enlarged to show its component sand-grains: d, Pilulina Jeffrey sii: e, portion of the test enlarged 

 showing the arrangement of the sponge-spicules. 



these two forms should present themselves in the same dredging; and 

 that there should be no perceptible difference in the character of their 

 sarcode-bodies, which, as in the preceding case, have a dark-green hue. 

 The Marsipella elongata (Fig. 320, d), on the other hand, is somewhat 

 fusiform in shape, and has its two extremities elongated into tubes, with 

 a circular orifice at the end of each. The materials of the < tests ' differ 

 remarkably according to the nature of the bottom whereon they live. 

 When they come up with ' Globigerina mud,' in which sponge-spicules 

 abound, whilst sand-grains are scarce, they are almost entirely made up 

 of the former, which are ( laid ' in a sort of lattice- work, the interspaces 

 of which are filled up by fine sand-grains; but when they are brought up 

 from a bottom on which sand predominates, the larger part of the ' test ' 

 is made up of sand -grains and minnte Foraminifera, with here and there 

 a sponge-spicule (Fig. 320, d, f). In each case, however, the tubular 

 extensions (one of which sometimes forms a sort of proboscis, e, nearly 

 equalling the body itself in length) are entirely made up of eponge-spic- 



