One of the most valuable lexicon finds: Amarakośa defines Ilvalāḥ by a relative clause — 'the stars which dwell in the head-region of that [Deer]' — so the anatomy is stated by the lexicon itself, not inferred. Colebrooke glosses 'Stars in his head', following directly on 'Orion'. Cognate/variant of Invakā already on file (the Vedic Invakā/Ilvalā alternation); this is the classical form with an explicit definition attached, and the Śārdūlakarṇāvadāna's 'three stars, deer's-head-shaped' independently confirms the group.
इल्वलाः Ilvalāḥ
the stars of Orion's head · λ, φ¹, φ² Orionis · Orion
Attestations
Devanagari transcribed by the compiler from the page FACSIMILE (archive.org scan leaf n220 = printed p. 118) because the archive.org OCR of this volume is unusable for Devanagari; the page image itself was fetched in this session at https://archive.org/download/in.ernet.dli.2015.292705/page/n220.jpg . Every numeral was re-read at full scan resolution. Cross-checked against a second, independent scan of the same Ray edition at https://archive.org/download/siddhantadarpanachandrashekarsimha1897_252_Z/ , which agrees character for character on the figures. Round brackets and the figures in them are the PRINTED EDITION'S own: (n) is the serial number of the asterism/star, the figure after it the edition's decoding of the preceding bhūtasaṅkhyā word-numeral, so no numeral has been silently converted here. A handful of the compound word-forms in this worn 1899 type are uncertain and are marked in this database as read, not emended; the FIGURES, which carry the astronomy, were verified at high magnification in both scans.
★ A COORDINATE FOR THE ILVALAS — THE FIRST ANYWHERE IN THIS DATABASE, AND IT DOES NOT AGREE WITH THE AMARAKOŚA GLOSS. XII.28 places 'three stars standing in the middle, arrow-like (iṣvābhakāḥ)' to the north-east of the star of XII.27 (Rigel), and gives them a dhruva of 61° and a southern śara of 23°. In Sāmanta's frame the three Belt stars stand at 59°51' / 23°37' S (δ), 60°50' / 24°34' S (ε) and 61°53' / 25°20' S (ζ) — his single pair of figures is the mean of the three to about 1°. So Sāmanta's Ilvalāḥ are ORION'S BELT, and his word for them, iṣvābhakāḥ ('arrow-like'), identifies them with the Vedic Iṣus trikāṇḍā, the three-jointed arrow, already in this database as δ, ε, ζ Orionis. This conflicts with the Amarakośa's definition of the Ilvalas as the stars 'that dwell in the head-region' of the Deer (λ, φ¹, φ² Orionis), which are 10° further north and 10° less in southern latitude. Either the name migrated within Orion, or the two traditions never meant the same three stars.