In the history of Middle English poetry two groups of stanzas must be distinguished: _divisible_ and _indivisible_ stanzas (the _one-rhymed_ stanzas being included in the latter class). The divisible stanzas consist either of two equal parts (_bipartite equal-membered stanzas_) or of two unequal parts (_bipartite unequal-membered stanzas_) or thirdly of two equal parts and an unequal one (_tripartite stanzas_). Now and then (especially in Modern English poetry) they consist of three equal parts. These three types are common to Middle and Modern English poetry. A fourth class is met with in Modern English poetry only, viz. stanzas generally consisting of _three_, sometimes of _four_ or more _unequal parts_. All the kinds of verse that have been previously described in this work can be used in these different classes of stanzas, both separately and conjointly. In each group, accordingly, _isometrical_ and _anisometrical_ stanzas must be distinguished. Very rarely, and only in Modern English, we find that even the rhythm of the separate verses of a stanza is not uniform; iambic and trochaic, anapaestic and dactylic, or iambic and anapaestic verses interchanging with each other, so that a further distinction between _isorhythmical_ and _anisorhythmical_ stanzas is possible. § =224.= The =bipartite equal-membered= stanzas, in their simplest form, consist of two equal periods, each composed of a prior and a succeeding member. They are to be regarded as the primary forms of all strophic poetry. The two periods may be composed either of two rhyming couplets or of four verses rhyming alternately with each other. Specimens of both classes have been quoted above (§ 78). Such equal-membered stanzas can be extended, of course, in each part uniformly without changing the isometrical character of the stanza. § =225.= The =bipartite unequal-membered= stanzas belong to a more advanced stage in the formation of the stanza. They are, however, found already in Provençal poetry, and consist of the 'forehead' (_frons_) and the 'tail' or veer (_cauda_). The _frons_ and the _cauda_ differ sometimes only in the number of verses, and consequently, in the order of the rhymes, and sometimes also in the nature of the verse. The two parts may either have quite different rhymes or be connected together by one or several common rhymes. As a simple specimen of this sort of stanza the first stanza of Dunbar's _None may assure in this warld_ may be quoted here: frons: {_Quhome to sall I complene my wo, { And kyth my kairis on or mo?_ { _I knaw nocht, amang riche nor pure, cauda: { Quha is my freynd, quha is my fo; { For in this warld may non assure._