The Dharma Kanda (Preta Kanda) of Garuda Purana contains a great detail on description of hell, the journey of our soul after death. It also contains detailed explanation of cremation rites to be performed for the welfare of the soul. It is in the format of question and answer between Garuda and Lord Krishna. One of the queries raised by Garuda is as follows:
102. If a man dies out of station and his bones too are destroyed, then how should the rite of cremation be performed. Tell me, O lord of the world!
This query is regarding tragic death caused due to accidents, suicide, due to animals etc., Lord Krishna says there is no other rite besides Narayana Bali which purifies the soul. Lord Krishna answers the query as follows.
Lord Kṛṣṇa said
104-109. O Garuda, hear. I shall now tell you the great secret about the rite of death for those who die through serpent, tiger, toothed, head.breaking horned animals, disease, stone, water, brāhmaṇa, dog, nails, iron; those who die of hunger, poison, fire and cholera; those who are killed by a bull, a thief, a cāṇdāla, a woman in her menses, Śaunaki, Śūdra, washerman; those who commit suicide or die by fall from a tree, bill, wall or precipice; those who die in water, on cot, in firmament, in bondage; those who are killed by Ūrdhvocchiṣṭa, Ardhocchiṣṭa or Ubhayocchiṣṭa; those who die of wounds by weapon on horseback.
[Dharma Kanda chapter 4]
He also mentions those who are killed by Ūrdhvocchiṣṭa, Ardhocchiṣṭa or Ubhayocchiṣṭa (bolded in English translation). Following is Sanskrit verse for the translation in bold.
ūrdhvocachiṣṭādharocchiṣṭobhayocchiṣṭāstu ye mṛtāḥ /
śastraghātairmṛtā ye cāsyaśvaspṛṣṭāstathaiva ca // GarP_2,4.109 //
The word Ūrdhva means vertical or higher. Ubhaya means two or bi and Artha means half. From the formation of words, it seems like it is talking about some classification. What is this classification based on? Who/which are these species?