THE FAMILY MILIOLlDiE 77 



develops a coiled series, as S^ylroloculiua, piano- 

 spiral, but constricted and partially septate at 

 either end of its axis of elongation. The next step is 

 shown in Mil iolina (vera), where the alternate series of 

 partially divided segments are not disposed in one plane 

 in their subspiral manner, but in the course of growth 

 are turned on the longer axis of the shell three or five 

 times in one complete revolution, as the case may be. 

 An apparently simple form, Biloculina, which exter- 

 nally appears to be a series of chambers placed 

 oppositely against the longer axis of the shell, is 

 evidently derived from the milioline form, since, 

 although its form A is constructed on this plan, 

 form B, with the microspheric chamber, commences in 

 many of the species, as Munier Chalmas and Schlum- 

 berger have showm, with a milioline form of shell 

 of the quinqueloculine type — that is, having five 

 chambers in one whorl — and only takes on the 

 biloculine arrangement in the adult stage. 



Labyrinthic modifications of the septate types of 

 shell growth are often found among the Foraminifera, 

 emd F ah idaria is an instance of such in the Miliolid.e. 

 This genus resembles a Biloculina externally, but the 

 chambers within are subdivided by meandering parti- 

 tions of the secondary shell-growth. 



The sub-families of the MilioHncc and the Penero- 

 jjlidimc are connected by an annectent group, the 

 Haiieriniuo'. The genera in this division resemble 

 Spiroloculiiup in the earlier part of the shell, in being 

 piano-spiral and septate, but they have their septa 

 arranged without regard to any ratio with the whorls, 



