‘In medio’ is explained by Donatus of the “impluvium,” perhaps rightly, comp. 2. 512 foll., where a bay-tree grows in the “impluvium” of Priam's palace. We must not however expect to be able to trace such details in the description of these vast shadowy realms. Heyne explains it “in medio vestibuli:” see on v. 285. “Ramos et bracchia tendens” G. 2. 296.
 “Opaca, ingens” 3. 619. The notion of dreams perched like birds on a tree Heyne traces to Il. 14. 286 foll., where Sleep, taking the form of a bird, perches on one of the trees of Ida, before coming down upon Zeus. Virg. may mean that the dreams are actually in the form of birds, as Henry thinks, comp. Sil. 13. 595 foll., who, imitating this passage, represents a yew on the banks of Cocytus as peopled by noisome birds. ‘Volgo’ may go either with ‘ferunt’ or with ‘tenere:’ but the latter seems more forcible. Wagn. comp. 3. 643, “habitant ad litora volgo.” In Od. 24. 12 the δῆμος Ὀνείρων is reached before the shades.
 Vana seems to mean fallacious as well as unsubstantial. Comp. the distinction between “verae umbrae” and “falsa insomnia” below vv. 894 foll. “Ne vana putes haec fingere somnum” 8. 42. ‘Haerent’ sc. ‘somnia.’ The parallels to this change of construction quoted by Wagn. Q. V. 34. 4 are mostly instances like 4. 263, where the subject of the second verb is the same as that of the first, but the first verb is constructed with a relative clause which is dropped in the second. One however comes tolerably near, 9. 593, “Cui Remulo cognomen erat, Turnique minorem Germanam nuper thalamo sociatus habebat.” Serv. and the older commentators suppose Virg. to refer to a notion that dreams become false at the fall of the leaf.
 Praeterea may be beside the dream-laded elm, which we must then suppose to be in the middle of the vestibule, or besides the shapes mentioned vv. 274 foll. ‘Monstra ferarum’ = “monstruosae ferae,” as “monstra deum” 8. 698 = “monstruosi Di.” The figures here are not personifications, but mythological monsters. Hom. knows nothing of them, though he makes Ulysses afraid lest Persephone should send the Gorgon's head from Hades against him Od. 11. 634: but Aristoph. Frogs 143, 277, speaks of wild beasts which have to be encountered immediately on crossing the infernal lake.
 Stabulant neuter, G. 3. 224. The word is appropriate to the Centaurs. ‘Scyllae’ may be meant to include the two Scyllas, as the daughter of Nisus was turned into a monster according to one legend (see on E. 6. 74), or the plural may be rhetorical, like Milton's “Hydras and Chimaeras dire.” It would almost seem as if Virg. wished them to be conceived of as a monstrous race, like the Centaurs. Lucr., whom Virg. doubtless had in view, speaking philosophically, treats them as a class, “Centauros itaque et Scyllarum membra videmus, Cerbereasque canum facies,” 4. 732, and again “Centauros . . . Scyllas et cetera de genere horum” 5. 891 foll.
 ‘Centumgeminus’ = “centuplex,” as “tergeminus” 4. 510 = “triplex,” “septemgeminus” v. 801 below = “septemplex.” The latter part of the compound has no very precise force, as is frequently the case in compounds in Greek, though the notion probably is that as “geminus” indicates repetition, “tergeminus” &c. may indicate a thing repeated three &c. times. “Tergeminus” is applied by Lucr. 5.28 to Gorgon, who had three bodies. Briareus had not a hundred bodies, but a hundred hands (Il. 1. 402 foll.), so that the expression is far from exact. Possibly however as Virg. (following Apollodorus) gives him fifty heads 10. 565 foll., he may have given him a hundred here. In Hom. there seems no reason for supposing him to have had more than one. The word is said to occur only in Val. F. 6. 118, where it is applied to the hundred-gated Thebes. ‘Belua Lernae,’ the Hydra, called “Lernaeus anguis” 8. 300, “Lernaea pestis” Lucr. 5.26.
 Stridens of the Hydra, as elsewhere of serpents. The Chimaera is called ‘flammis armata,’ as the Parthian arrow is called “armata felle veneni” 12. 857. Wakef., thinking the expression commonplace, ingeniously proposed ‘animata,’ which would produce a translation, though not perhaps a very Virgilian one, of Hom.'s δεινὸν ἀποπνείουσα πυρὸς μένος αἰθομένοιο, Il. 6. 182. The Chimaera is one of Turnus' cognizances, 7. 785 foll.
The ‘forma tricorporis umbrae’ is
Geryon, mentioned again 7. 662., 8. 202.
Aesch. Ag. 870 calls him τρισώματος, and
Lucr. 5.28 talks of “tripectora tergemini
vis Geryonai.” Sil. uses the word ‘tricorpor’
twice, each time of Geryon. The
words ‘forma umbrae’ (for ‘formae’ see
on 3. 591) sufficiently indicate the spectral
and unsubstantial nature of the appearances,
pointed out by the Sibyl in the following
lines. Some of these monsters had
been actually killed, so that it was natural
that they should appear spectrally in
Hades; others, like the Harpies, were
products of the infernal world (comp. 3.
214), and though when appearing on earth
they may have had bodies, they may be
supposed to be divested of them in the
shades, where spirit acts upon spirit. The
train of thought may be the same as that
in Hom. (Od. 11. 602), where though
Hercules himself is among the gods, his
εἴδωλον is in the shades (comp. Shelley's
‘Phantasm of Jupiter’ in the Prometheus
Unbound): or Virg. may have been influenced
more or less by a philosophical
motive, intending to hint at the unreality
of these terrible shapes. The words of
Serv. may be worth quoting, “‘Harpyiaeque:’
aut iam mortuas intellige, aut secundum
Platonem et alios simulacra licet
vivarum illic fuisse. Nam dicunt esse
omnium rerum ideas quasdam, i. e. imagines,
ad quarum similitudinem procreantur
universa.” Serv. also tells us that
after these lines four others were inserted
by some, who believed them to have been
left by Virg., but omitted by those who
revised his work. It will be seen that
they are of the same quality as those quoted
on 3. 204:
“Gorgonis in medio portentum inmane
Vipereae circum ora comae cui sibila torquent,
Infamesque (qu. informesque?) rigent oculi, mentoque sub imo
Serpentum extremis nodantur vincula caudis.
 Docta, instructed, perhaps by Hecate, v. 565 below. But the word often means little more than wise or skilful: see Forc. ‘Tenuis vitas’ G. 4. 224. ‘Sine corpore:’ see on G. 4. 475, where, as in v. 303 below, Virg. is not quite consistent with his language here.
 Virg.'s words are a paraphrase of τοὶ δὲ σκιαὶ ἀΐσσουσιν Od. 10. 495, translated by Cic. De Div. 1. 40, “ceteros umbrarum vagari modo.” The kind of motion is connected with the want of substance and stability. ‘Cava imagine’ means more than “nube cava” 1. 516, “cava umbra” 2. 360 note, expressing not merely that the spirits are enclosed by the visible shape, but that the shape is essentially hollow, ψυχὴ καὶ εἴδωλον, ἀτὰρ φρένες οὐκ ἔνι πάμπαν (Il. 23. 105: comp. Od. 10. 493). ‘Admoneat—inruat:’ see on 5. 325.
 In Hom. Ulysses' sword operates as a real terror to the ghosts (see on v. 260 above). The legend was that Hercules drew his sword on the Gorgon when he went down to the shades, and was reassured by Hermes as Aeneas here is by the Sibyl (Apollodorus 2. 5. 12: Schol. on Il. 8. 368). ‘Diverberet’ 5. 503 note.
[295-316] ‘Next they see the way to Acheron. Charon is there with his ferryboat, old and squalid, but vigorous. Ghosts keep crowding to the boat: some of them are admitted, others rejected.’