ers. The Muse referred to is
probably Clio, the Muse of History)
haughty > noble, high-minded
mask > disguise [herself]

263 and loath the lays that long to lowly swains.

lays > songs
long to > befit, beseem; are appropriate to
swains > young men

264 That lifts your notes from shepherds to kings,
265 So like the lively lark that, mounting, sings.
266
267 Your lovely Rosalind seems now forlorn,

Rosalind > (Colin Clout's love in _SC_)

268 and all your gentle flocks forgotten quite,
269 Your changed heart now holds your pipes in scorn,
270 those pretty pipes that did your mates delight.
271 Those trusty mates, that loved you so well,
272 Whom you gave mirth: as they gave you the bell.

the bell > the prize; first place (before cups were awarded to winners
of horse-races, etc., a little gold or silver bell was presented as
the prize)

273
274 Yet as you erst with your sweet roundelays

erst > previously, at first
roundelays > {Short, simple songs}

275 did stir to glee our lads in homely bowers:

glee > delight
bowers > rooms, chambers

276 So might you now, in these refined lays,
277 delight the dainty ears of higher powers.
278 And so might they in their deep scanning skill

scanning skill > ability to understand [poetry]

279 Allow and grace our Colin's flowing quill.
280
281 And fair befall that _Faery Queen_ of yours,

fair > [fair fortune]

282 in whose fair eyes love linked with virtue sits:
283 Infusing by those beauties fierce divine,

divine > [and divine]

284 Such high conceits into your humble wits,

conceits > ideas

285 As raised has poor pastor's oaten reed

pastor's > shepherd's
oaten reed > (Of which shepherds' pipe were supposedly made)

286 From rustic tunes to chant heroic deeds.
287
288 So might your Redcross Knight with happy hand

happy > fortunate

289 victorious be in that fair island's right:

that fair island > [Britain]

290 Which you do veil in type of Faery Land,
291 Eliza's blessed field, that Albion hight,

Eliza > [Elizabeth]
hight > is called

292 That shields her friends, and wars her mighty foes,

wars > [wages war upon]

293 Yet still with people, peace, and plenty flows.

still > ever

294
295 But (jolly shepherd) thoug