58 MANUAL OF ZOOLOGY. 



code. At the summit of the column is a minute aperture sur- 

 rounded by a brush of spicules, and the whole structure is fixed 

 by the pedestal to some solid object. 



To the Polycystina, the Foraminifera are obviously and 

 closely allied. They agree in the nature of the sarcode-body, 

 in the filamentous, inosculating pseudopodia, and in the phe- 

 nomenon of a pseudopodial circulation of granules. They 

 differ solely in the nature. of the "test," which is calcareous or 

 arenaceous in the Foraminifera, but is always siliceous in the 

 Polycystina. 



Bathybius, Coccoliths, and Coccospheres. — It may be 

 as well to notice here a singular organism which is certainly 

 referable to the Rhizopoda, though its exact affinities are 

 doubtful. Certain minute oval or rounded bodies have long 

 been known as occurring attached to the surface of the shells 

 of Foraminifera, and they were originally described by Pro- 

 fessor Huxley under the name of coccoliths. Subsequently it 

 was discovered by Dr Wallich that these singular bodies occur 

 not only in the free condition, but also attached to the external 

 surface of little spherical masses of sarcode to which he gave 

 the name of coccospheres. The coccospheres are enclosed in a 

 delicate envelope apparently of a calcareous nature, and are 

 studded at nearly regular intervals by the coccoliths. More 

 recently still, it has been discovered by Professor Huxley that 

 both the coccoliths and the coccospheres are embedded in masses 

 of protoplasmic or sarcodic substance, covering wide areas of 

 the sea-bottom, to which they bear the same relation that the 

 spicules of sponges or of Radiolaria do to the soft parts of 

 these animals. To this undefined and diffused protoplasm 

 with its contained coccoliths and coccospheres the name Bathybius 

 has been applied by Professor Huxley. Its exact position, as 

 already said, is doubtful ; but it is believed by Dr Carpenter to 

 be a rudimentary form of the Foraminifera, and to be somewhat 

 allied to the ancient Eozoon. A curious point as regards the 

 coccoliths has recently been brought to light by Dr Giimbel, the 

 celebrated palaeontologist, who believes that he has succeeded 

 in demonstrating in them the existence of cellulose, or of some 

 substance closely allied to cellulose. He has also shown that 

 bodies similar to, if not identical with, coccoliths, occur in for- 

 mations as old as the Potsdam Sandstone (Lower Silurian) of 

 North America. More recently still, Mr Carter has shown that 

 coccoliths occur in great numbers in the Laminarian zone, and 

 he asserts them to be solitary, unicellular, calcareous Algae. 

 He describes them under the name of Melobesia unicellularis 

 and M. disats, according as they are oval or round ; and he 



