102 



FAMILY MILIOLIDA. 



narrower again towards their anterior extremities, where their terminations appear as the 

 pores on the apertural- plane whicli closes in each segment as its formation is completed. 



149- The idea of the structure of the composite animal which we gain from the 

 examination of these sections of the shell is fully borne out by the examination of the 

 silicified " casts " of the interior, which Messrs. Parker and Rupert Jones have been fortunate 

 enough to obtain (p. 10) ; for these casts, which exactly represent the form of the sarcode-body 

 whose place they have occupied, exhibit just the arrangement and connections which might 

 have been predicated. The whole body (Fig. XXIII) is made up of a series of minute elongated 

 sub-segments, united together at their extremities, in the mode to be presently described, into 

 groups which represent the principal segments of Foraminifera of less complex type. Every 

 such group consists of several rows (usually four or more) of sub-segments, arranged vertically 



Fig. XXIII. 



Portion of an Internal Cast of an Alveolim of complex type -.—a, a, a, a, superficial series of sub-segments ; 

 b, I, b, subjacent series ; cc, cc, longitudinal stolons ; d, d, vertical columns. 



one over the other ; but the sub-segments {a, a) forming the superficial layer are of only about 

 half the breadth of those [b, h) of the subjacent layer, and are about twice as numerous. The 

 superficial sub-segments spring by slender peduncles from a band or " stolon" (c, c) that passes in 

 a longitudinal direction from one end of the series to the other, and terminate at their anterior 

 extremity in a similar band. The sub-segments that form the subjacent layers spring 

 posteriorly by constricted necks from vertical " columns " {d, d) which occupy the " well-stair- 

 cases," and terminate anteriorly in similar columns ; and the columns forming each of the rows 

 that intervene between one segment and another are brought into lateral connection by two 

 or more " stolons " which pass along the entire series. Thus although the sub-segments 

 themselves have no direct communication with each other, they are intimately united into 

 one system by the intervention of these " columns " and " stolons." Looking to the place 

 of the connecting passages in the transverse section (fig. 14), it becomes obvious that the 

 stolons which occupy them are formed by the union of the pseudopodial extensions that 

 issue from the pores of the aperture. A coalescence of those proceeding from the four sets 

 of pores (one of them close to the inner margin of the spire) corresponding to each other 



