45. LAVDVM. 'Deeds meriting praise'; compare 87 'tuas ... laudes ... recentes'. The meaning is found even in prose: see Caesar BC II 39 4 'haec tamen ab ipsis inflatius commemorabantur, ut de suis homines laudibus libenter praedicant' and the other passages cited at OLD laus1 3b.
46. ACTORVM. AVCTORVM (BCHL) is possible enough; but actorum accords better with the preceding laudum.
46. CADVCA. 'Impermanent'. The sense is frequent in Cicero: see Rep VI 17 'nihil est nisi mortale et caducum praeter animos' and Phil IV 13. Elsewhere in Ovid the usual sense of the word is 'ineffectual': see Fast I 181-82 'nec lingua caducas / concipit ulla preces, dictaque pondus habent' and Ibis 88 'et sit pars uoti nulla caduca mei'. Similar uses at Her XV 208 & XVI 169.
47. CARMINE FIT VIVAX VIRTVS, EXPERSQVE SEPULCRI / NOTITIAM SERAE POSTERITATIS HABET. For the immortality given by verse, compare from Ovid Tr V xiv 5 (to his wife) 'dumque legar, mecum pariter tua fama legetur' and EP III ii 35-36 (to those friends who assisted him) 'uos etiam seri laudabunt saepe nepotes, / claraque erit scriptis gloria uestra meis'. The topic is closely related to that of the poet's own immortality, for which, in Ovid, see xvi 2-3 'non solet ingeniis summa nocere dies, / famaque post cineres maior uenit' and Met XV 871-79.
For other poets' treatment of the immortality given by verse, see Prop III ii 17-26, Hor Carm IV ix, Pindar Nem VII 11-16, Gow on Theocritus XVI 30, and Murgatroyd on Tib I iv 63-66.
47. VIVAX VIRTVS. Compare Hor AP 68-69 'mortalia facta peribunt, / nedum sermonum stet honos et gratia uiuax'.
47. EXPERSQVE SEPVLCRI. The diction of this line is very elevated: Professor R. J. Tarrant compares Met IX 252-53 (Jupiter speaking of Hercules) 'aeternum est a me quod traxit, et expers / atque immune necis' and Cons Liu 59-60 'Caesaris adde domum, quae certe funeris expers / debuit humanis altior esse malis'. The following line's notitiam ... habet is in comparison an anticlimax.
49. TABIDA CONSVMIT FERRVM LAPIDEMQVE VETVSTAS. Iron and flint were proverbial for hardness: compare x 3-4 'ecquos tu silices, ecquod, carissime, ferrum / duritiae confers, Albinouane, meae?', Her X 109-10, AA I 473-76, Met XIV 712-13, Fast V 131-32, Tr IV vi 13-14, and EP II vii 39-40; other passages are cited by Smith at Tib I iv 18 'longa dies molli saxa peredit aqua'. At I 313-16, Lucretius, discussing the invisible wearing away of substances, says 'stilicidi casus lapidem cauat, uncus aratri / ferreus occulte decrescit uomer in aruis, / strataque iam uolgi pedibus detrita uiarum / saxea conspicimus'.
51. SCRIPTA FERVNT ANNOS. The phrase completes the sentence begun in the previous distich, as is shown by the parallel passages Am I x 61-62 'scindentur uestes, gemmae frangentur et aurum; / carmina quam tribuent, fama perennis erit' and Am I xv 31-32 'ergo cum silices, cum dens patientis aratri / depereant aeuo, carmina morte carent'.
51. FERVNT. 'Withstand'; the same sense at Tr V ix 8 'scripta uetustatem si modo nostra ferunt', Cic Am 67 'ea uina quae uetustatem ferunt', Silius IV 399-400 'si modo ferre diem ... carmina nostra ualent', and Quintilian II 4 9 'sic et annos ferent et uetustate proficient'.