46 POPULAE ILLUSTRATIONS OF 



figured in all stages of the shell growth in his truly magnificent work 

 on these creatures. In the centre of each shell there is found a 

 single somewhat pear-shaped chamber (&, Fig. 67), and a larger one 

 immediately surrounding it.* From this chamber a series of canals 

 are sent off, terminating as shown above in a chamberlet, as it is 

 called, which is represented by the figures on my shilling ; and the 

 first zone being then formed, the pseudopodia enable the animal to 

 increase the shell outwardly until it attains in some instances, as I 

 have before remarked, nearly one inch diameter. It is possible, by 

 decalcification with a weak acid, to remove the shell, and leave the 



Fig. 67. 



Fig. 66. 



Fig. GQ.Lagynis Baltica (after Schultze), highly magnified. A, animal expanded, and 

 pseudopodia protruded from mouth , animal contracted into the bottom of shell 

 a, mouth. 



Fig. 67. Decalcified sarcodous animal of Orbitolites a, the sarcode which fills the canal 

 opening in the edge of the shell through which the pseudopodia are emitted 6, the 

 central sarcode or amoeba forming the animal of Orbitolites c, the segments of sarcode 

 connected with each other and with the central sarcode by the various canals. In the 

 shell the space occupied by these segments is called a " chamberlet." 



sarcode animal in situ. It will then have the appearance shown in 

 Fig. 67. The arrangement of the canals and the individuals which 

 make up the compound animal is well shown. The pseudopodia 

 proceed, as I have described, from the annular passages between the 

 outer row of segments, as they are called. In due season these 

 pseudopodia will form another concentric zone like that from which 

 the canal (a) proceeds which will then, in. like manner, be trans- 

 ferred to the edge of the new formation ; and so the Orbitolites will 

 increase in size. 



* I have not thought it necessary to give a figure of the shell, which is of 

 course an exact impression of Fig. 67. This must be borne in mind when I 

 am describing the chambers of the shell. 



