In the Mixteca tongue the imperfect is thus formed from the present, which carries with it the personal sign, and the perfect without its personal sign, a proceeding which, however rude and awkward it may be, shows a just appreciation of the peculiarity of this past tense, which expresses an action as going on, and therefore present in past time. The expression of continuous action is placed first, “I sin,” then this is more precisely defined by the mark of past time, “this was so;” _Yo-dzatevain-di-ni-cuvui_. _Yo_ is the sign of the present, _ni_ of the preterit, _di_ is the pronoun; the other two words, _to sin_ and _to be_: “I was sinning.” The sign of the present, _yo_, is probably an abbreviation of the verb _yodzo_, I stand upon or over something, and so there is a second auxiliary in the sentence. This may often be a means of discovering the origin of tense signs, as, especially in American tongues, tenses are often formed by the union of verbs, as also occurs in Sanscrit and Greek. The Othomi distinguishes certain past tenses, which, however, are separated by other characteristics, by a prefixed _xa_, which is called the third person singular of a substantive verb. As these tenses are precisely those in which the action must be completed, the perfect, pluperfect and future perfect, not, however, the imperfect and past aorist, such a connection is very suitable. Of this verb we have only _xa_, and there is another substantive verb _gui_, which itself takes _oca_ in its conjugation. The Totonaca language unites the perfect, in the person spoken of, with the third person singular of the future of the substantive verb, to form a future perfect. This is no completed form, but only an awkward sequence of two verbs; _yc-paxquilh-na-huan_, literally, “I have loved, it will be,”=“I shall have loved.” In similar manner the substantive verb is used to form a tense of the subjunctive. The sign of both the perfects in this tongue is the syllable _nit_, and _niy_ means “to die.” It is not improbable that this affix is derived from this verb. Death and destruction are suitable ideas to express the past, and some languages employ negative particles as signs of the preterit. In the Tamanaca this is not exactly the case, but the negative particle _puni_ added to a word which signifies an animate thing, intimates that it has died; _papa puni_, the deceased father, literally, “father not.” In the Omagua tongue the same word signifies old, dead, and not present.