As far as I know, it’s the only illustration of any sort in his travel writings, and in that sense, there might be a rather conscious parallel to the case of Walter Pater, who inserts as the frontispiece to his Renaissance, that ‘face of doubtful sex’ – a drawing attributed to Leonardo – and that’s it, that’s the only illustration in Pater. Similarly, I believe this is the only illustration, the only image appearing in Symonds’s works, or at least in his essay collections (I’m putting aside his book on Michaelangelo which is a rather different case).
So what I’m going to be talking about are these three different discursive settings for Antinous, one of which is very short, but nonetheless important. The first is a poem which he probably wrote around 1868. It was only published in 1878 in a collection called Many Moods, but it was indeed very probably written quite a few years before. The second is the essay, which is published in his Sketches and Studies in Italy and Greece, which comes out in 1879, the year after the poem is finally published. The third is really just a historical note in a pamphlet. Note that these three instances refer to perceptions which involve quite different views of Antinous and in the last one at any rate, the question of sculptures of Antinous is virtually irrelevant. What we have instead is a concentration on Antinous the historical figure and on his relationship to Hadrian.
Now the first instance therefore is the poem, written in 1868, in John Addington Symonds’s youth. It’s called ‘The Lotus Garland of Antinous’, and you could say that it’s really three things at once, and a lot of its interest derives from that particular fact. It’s a narrative, it’s a poem supposedly on the last days of Antinous, and – what makes it more interesting from our point of view – it draws very specifically on two antique poetic modes, or literary modes, in general. It begins as an ekphrasis in my view, that’s to say as a description couched in the way that classical descriptions of paintings and sculptures were managed by Greek and Roman Sophists, and it ends as a metamorphosis, in the very precise sense that Ovid gives to metamorphosis in his great book – the eternal classic of classical mythology for Western culture.
Just to begin with, however, here is the note that Symonds places in his edition of the poem, which very clearly shows the diversity of the sources that he’s looked at, and the fact that he’s not by any means simply looking at any one particular sculpture or a set of sculptures. He writes:

This poem was suggested by the colossal statue of Antinous with the attributes of Dionysus in the Rotondo of the Vatican, his portrait in relief in the Villa Albani, a passage relating to his death in the Augustan Histories, and a passage in Athenaeus on the crowns of Lotos worn in Egypt at his festival. I have attempted no decided solution of the problem offered by his mysterious death. Although I incline, for artistic purposes [note that this is, as we shall see later, something of a cop-out!], to the tradition of self-sacrifice, rather than to the opposite hypothesis of immolation at the hands of Hadrian, I am aware that his subsequent deification and the extraordinary respect paid to his memory in many parts of the Roman world, may have been prompted by the emperor’s remorse no less than by his gratitude or his affection.

And then he concludes the note by saying that ‘the history of the empire, rich as it is in motifs of romance and mystery, offers nothing stranger or more striking than the obscure life, the doubt-environed doom, and the immediate apotheosis of this court- favourite’.
Now I said it begins as an ekphrasis, and I suppose the ekphrasis I take as being closest to it is from Callistratus’ Descriptions, quite a late body of ekphrases, and all of them descriptions of sculpture in this case, written in the late third century. This is an ekphrasis on the statue of Narcissus. First of all the geographical placing. Callistratus: ‘There was a grove, and in it an exceedingly beautiful spring of very pure clear water, and by this stood a Narcissus made of marble. He was a boy, or rather a youth of the same age as the Erotes; and he gave out as it were a radiance of lightning from the very beauty of his body.’ This is the typical beginning of an ekphrasis on a sculpture, which places the sculpture as being within an imaginary background, but also immediately starts to talk about the light given out by the body; this being a play with the notion that the marble is giving out radiance, and that the marble is equated with the attractiveness and image of real flesh. So later on, a few lines down, the ‘garb which adorned him’ is as follows: ‘a white mantle, of the same colour as the marble of which he was made, encircled him: it was held by a clasp on the right shoulder and reached down nearly to the knees, where it ended, leaving free, from the clasp down, only the hand. Moreover, it was so delicate and imitated a mantle so closely that the colour of the body shone through, the whiteness of the drapery permitting the gleam of the limbs to come out.’