Balanoglossus in Mashail Island described it as a worm-like holothurian. The discovery of gill-slits in this animal by Kowalewsky (1865) led to creation of a special class Enteropneusta by Gegenbaur (1870). Bateson (1885) included them in Phylum Chordata. Hyman (1959), however, placed them near Echinodermata and gave Hemichordata a status of an independent phylum. This simple organism shows affinities with several diverse groups. Balanoglossus is a tuberculos or burrowing and exclusively marine animal. It is found in shallow waters between tide marks along the coast of warm and temperate oceans. Balanoglossus clavigerus is a U-shaped excavated in a sandy bottom Nemertines
Three subgroups lemma for all formula_13 and formula_11. Since these elements generate formula_20, we conclude that formula_21 and hence formula_4. [[Category:Theorems in group theory]] [[Category:Articles containing proofs]] [[Category:Lemmas]] Three subgroups lemma In mathematics, more specifically group theory, the three subgroups lemma is a result concerning commutators. It is a consequence of the Philip Hall and Ernst Witt's eponymous identity. In that which follows, the following notation will be employed: Let "X", "Y" and "Z" be subgroups of a group "G", and assume Then formula_4. More generally, if formula_5, then if formula_6 and formula_7, then formula_8. Hall–Witt identity If formula_9, then Proof of the