Ambulacraria Ambulacraria Ambulacraria or Coelomopora is a Superphylum of invertebrate phyla which includes echinoderms and hemichordates; a member of this group is called an ambulacrarian. Phylogenetic analysis suggest the echinoderms and hemichordates separated around 533 million years ago. The Ambulacraria are part of the deuterostomes, a larger clade that also includes the Chordata, Vetulicolia and Saccorhytus. The two living clades with representative organisms are: The group Xenoturbellida (two species of worm-like animals) has previously been considered to be in this clade, but is now considered to be placed more basally among Metazoans. Fossil taxa that may lie on the stem lineage:
Lattice of subgroups finite lattice is isomorphic to a sublattice of the subgroup lattice of some finite group . Subgroups with certain properties form lattices, but other properties do not. However, neither finite subgroups nor torsion subgroups form a lattice: for instance, the free product formula_3 is generated by two torsion elements, but is infinite and contains elements of infinite order. The fact that normal subgroups form a modular lattice is a particular case of a more general result, namely that in any Maltsev variety (of which groups are an example), the lattice of congruences is modular . Lattice theoretic information about the