167. _Genealogical Tree of the Larcoidea._--The suborder #Larcoidea# presents in the structure, composition, and development of its variously formed lattice-shells much more complicated relations than the other #Sphærellaria#; it is essentially distinguished from them by the characteristic ground-form of its lattice-shells, which is a "lentellipsis" or a triaxial ellipsoid (also the ground-form of the rhombic crystallographic system, the rhombic octahedron). Hence all parts of the body are regularly disposed with respect to three different dimensive axes; all three axes, perpendicular one to another, are isopolar but of different lengths; the longest is the vertical main axis, the mean the horizontal frontal axis, the shortest the horizontal sagittal axis. In the great majority of the #Larcoidea# the lentelliptical ground-form is indicated in the central capsule, even when it is not at once obvious in the skeleton. Since such lentelliptical central capsules are developed even in _Actissa_ (_Actilarcus_, p. 16), it is possible that the simplest #Larcoidea# may have arisen directly from these by deposition of a simple lentelliptical lattice-shell in the sarcodictyum, on the surface of the calymma (_Cenolarcus_, Pl. 50, fig. 7). It is more probable, however, that these simplest forms (_Cenolarcus_, _Larcarium_) have been developed from the simplest #Sphæroidea# (_Cenosphæra_), by the spherical body growing unequally in the three dimensions of space. It appears especially likely {cxi}from a study of the concentrically disposed lattice-shells of some #Larcoidea# (_Coccolarcus_, _Larcidium_, Pl. 50, fig. 8), in which the inner medullary shell is spherical, the outer cortical shell more or less elliptical. In the great majority of #Larcoidea# the latter arises in quite a peculiar manner, three broad lattice-zones, which are developed in three planes at right angles to each other, growing out from a small spherical or lentelliptical medullary shell, _Trizonium_, _Larnacilla_ (compare pp. 600, 615, 628, &c.).