The vaitālīyam and aupacchandasikam are two closely-related meters that combine the principles of the vr̥ttam and jātiḥ classes: they are mora-counting at the beginning of a verse line, and syllable-counting toward the end. They are probably “transitional” forms, since they do not occur in the oldest texts (which are dominated by vr̥ttam forms) and are very rare in classical texts (where jātiḥ forms occur freely); you are most likely to find them in the canonical and postcanonical literature of the Buddhists and Jains.
They are ardhasama meters, which means that they are divided into four quarters, with the two even quarters (the first and third) and the two odd quarters (the second and fourth) different from each other in length. The vaitālīyam has 14 moras in its odd lines and 16 in its even lines. But the last eight moras of every line is taken up by the same syllabic pattern: ऽ।ऽ।ऽ. The aupacchandasaka is identical, except that it has an additional heavy syllable at the end of each syllable. Therefore it has 16 and 18 syllables in its odd and even lines, respectively, and both end with the fixed cadence ऽ।ऽ।ऽऽ. Any configuration of syllables can come before the fixed cadence.
vaitālīyaṁ dviḥsvarā ayuk pādē yug vavasō ’ntē rlgaḥ
g aupacchandasikam
vaitālīyam antē lau
aupacchandasikaṁ tē
vaitālīyaṁ caturdaśāyuji hāḥ
yuji ṣōḍaśa
bhadvayōr antē
bhā caupacchhandasikam
vaitālīyaṁ rlganaidhanāḥ
ṣaḍayukpādōṣṭau samaś calaḥ
na samō ’tra parēṇa yujyatē
naitāḥ ṣaṭ ca nirantarā yujōḥ
ryāvantē śēṣapūrvasāmyād
aupacchandasakaṁ vadanti santaḥ
datrayam ayujōr mukhē
dacatuṣkaṁ ralagās tu śēṣataḥ
vaitālīyaṁ tad ucyatē
laghuṣaṭkaṁ na nirantaraṁ yujōḥ
vaitālīyōpamaṁ mukhaṁ cēd
aupacchandasikaṁ rayau tu pr̥ṣṭhē
viṣamāṁhrigataṁ yad atra tad
vaitālīyasya lakṣaṇam
paritō viṣamābhidhānabhr̥d
vaitālīyaṁ tad ucyatē
aupacchandasikasya lakṣaṇaṁ yat
samapādōditam atra vartatē cēt
pratipādaṁ tan nāma tatsamaupa-
cchandasikaṁ chandōvidaiḥ praṇītam
ṣaḍ viṣamē ’ṣṭau samē kalās
tāś ca samē syur nō nirantarāḥ
na samātra parāśritā kalā
vaitālīyē ’ntē ralau guruḥ
paryantē ryau tathaiva śēṣam
aupacchandasikaṁ sudhībhir uktam
ōjē ṣaṇmātrā rlgantā yujy aṣṭau na yuji ṣaṭ santataṁ lā na samaḥ parēṇa gō vaitālīyam
ryāntā aupacchandasakam
This example was recited by H. V. Nagaraja Rao and recorded by Gil Ben-Herut in 2006. The translation is mine.
If even flowers are capable of stealing away my life,
just because of their contact with her body,
then my god, if fate wants to strike me down,
is there anything at all that won’t serve the purpose?
If this garland can kill me,
when placed on my chest, then what will not kill me?
Even poison can sometimes restore one to life,
and life-restoring medicine can, by the will of god, be poison.