ON THE LIFE-HISTORY OF THE FORAMINIFERA. 161 



(/) Cycloclypeus Carpenteri, Brady. Figs. 52-54. 



I obtained a few examples of this rare species to the south- 

 east of Nomuka, in the Tonga Islands, at a depth of from 

 20 to 40 fathoms. 



On decalcifying them two were found to have been pre- 

 served with the protoplasm contained in the shell. One of 

 these, which measured about 1 eentim. in diameter, was 

 mounted whole, after staining with picro-carmine, and sections 

 were cut of the other (which was smaller) parallel to the plane 

 of the disc. 



In both specimens large chambers, resembling to some 

 extent the primitive disc of OrbitoUtes complanata, Lamk., 

 occupy the centre of the shell (fig. 52). These consist of: (1) 

 A somewhat oval chamber which appears to be the megalo- 

 sphere, measuring 300 x 205 /m. (Owing to the shrivelled con- 

 dition of the walls of the inner chambers, which consist of a 

 thin apparently chitinous layer, these numbers are only approxi- 

 mately correct.) (2) A very large crescent-shaped chamber, in 

 the concave side of which the megalosphere lies. The length 

 in a straight line is 610 /tt, and the greatest breadth 310 /x. In 

 the sections a single short canal can be detected passing from 

 the megalosphere to the second chamber, at about the middle 

 of the concave side. (3) Another somewhat crescent-shaped 

 chamber, enclosing the other side of the megalosphere ; while 

 its length is about equal to that of the second chamber, its 

 breadth is very much less (under 100 /a). This chamber appears 

 to be intermediate in character between the large chambers 

 and the small ones making up the surrounding annuli. 



The two crescent-shaped chambers thus surround the mega- 

 losphere. Their ends are in apposition, the third chamber 

 somewhat overlapping the second on the outer side, and they 

 communicate at either end by short canals passing from one 

 chamber to another. 



The first ring of chambers surrounds these three, communi- 

 cating with the crescentic chambers by several short canals, 



