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 or "(Dedekind's) modular law" (, ). Since for two normal subgroups the product is actually the smallest subgroup containing the two, the normal subgroups form a modular lattice. The Lattice theorem establishes a Galois connection between the lattice of subgroups of a group and that of its quotients. The Zassenhaus lemma gives an isomorphism between certain combinations of quotients and products in the lattice of subgroups. In general, there is no restriction on the shape of the lattice of subgroups, in the sense that every lattice is isomorphic to a sublattice of the subgroup lattice of some group. Furthermore, every