FORAMINIFERS. 



555 



times the length of the body. Every 'fibre exhibits an up and down stream of 

 granules suspended in clear hyaline sarcode. A diatom, infusorian, or other edible 

 prey, coming in contact with the pseudopods, is covered with a mass of protoplasm 

 formed by fusion of several filaments, drawn down to the mouth of the shell and 

 engulfed. Gromia moves by means of its pseudopods, which fix themselves and 

 draw the body along. When alarmed, the animal withdraws into its membranous 

 test. 



The sandy Foraminifera, which are mostly deep-sea types, are composed of 

 masses of sarcode, sometimes of considerable size, which form shells or cases of 

 agglutinated mud, sand-particles, or sponge-spicules. They frequently attain a 



a Hyperammina ramosa ; b and c, Astrorhiza limicola ; b, Entire ; c, Cut open. 



large size ; for instance, Baihysiphon, from the Atlantic and also from fourteen 

 hundred and twenty -five fathoms off Amboyna, forms a slender annul ated tube, two 

 inches in length, and open at each end, the walls of the tube being composed of 

 cemented sponge-spicules. Haliphysema is found in shallow water in the North 

 Atlantic in the form of minute club-shaped bodies, one-twentieth of an inch in 

 height, with the narrowed lower end attached by a disc to zoophytes, etc., and with 

 the surface bristling with sponge-spicules. Hyperammina, generally distributed in 

 from sixty to three thousand fathoms, makes a test of cemented sand-grains and 

 sponge-spicules, at first forming a globular chamber with a long branched neck, the 

 branches of which again branch. Astrorhiza forms stellate single-chambered shells 

 of fine mud, slightly cemented, and lined inside by a smooth membrane ; at the 

 ends of the arms are large openings for the pseudopods ; the diameter of the disc 

 is about one-fifth of an inch, and that of the entire shell about half an inch ; the 

 animal lives in comparatively shallow water (about twenty fathoms), in the North 

 Atlantic. Certain other sandy species are characterised by the regular form of 

 their shells, which resemble those of calcareous species. The imperforate cal- 

 careous species are usually milk-white. The shell possesses only one or a few 



