20 EHIZOPODA. 



maceration in dilute acid, the above arrangement 

 will be rendered still more evident {fig. 4, h). 



For the contents of the ovate cells are seen to 

 consist of segments of sarcode (cr, a, a), from which 

 stolons are prolonged into the interior of both the 

 radial and annular passages (p, p, p, and X, X). 

 Each of the concentric zones of segments is, in 

 all probability, produced by gemmation from the 

 zone immediately ^^^thin it, the segments of the 

 innermost zone having been oi'ic^inallv budded off 

 by extensions of the sarcode body contained in 

 the circumambient cell, which, again, in its turn, 

 is connected by means of a narrow stolon with the 

 pear-shaped mass of the same substance occupying 

 the interior of the central cell. There can be 

 also but little doubt that, in the living animal, the 

 radial stolons of sarcode which proceed from the 

 outermost annulus are enabled to send forth pseu- 

 dopodia through the marginal pores, the latter 

 being the only external apertures which the shell 

 of the Orbitolite possesses ; and analogy would 

 suggest that these pseud opodia ma}^ not only 

 serve for the prehension of food, but may also, by 

 the coalescence of several round the margin of the 

 shell, give rise to the deposition of successive 

 layers of calcareous matter. 



Such is the ordinary structure of Orbitolite. 

 But the same form is sometimes met with un- 

 der a much more complicated type, in which 

 the thickness of the entire shell is considerably 

 increased, and the marginal pores are seen to be 

 arranged in several rows, placed one above another. 

 Here the superficial cells, which in the simple 

 type are either round or oval, become nearly 

 rectilinear, having their long diameters placed at 



