Allen and Greenough's New Latin Grammar, section 359

Heavy Construction

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PECULIAR GENITIVES.

359.

Peculiar Genitive constructions are the following:

a. A poetical genitive occurs rarely in exclamations, in imitation of the Greek (Genitive of Exclamation):

dí immortalés, mercimóni lepidi (Pl. Most. 912), good heavens! what a charming bargain!
foedens heu taciti (Prop. iv. 7. 21), alas for the unspoken agreement!

b. The genitive is often used with the ablatives causá, gratiá, for the sake of; and the indeclinable ínstar, like; also with prídié, the day before; postrídié, the day after; tenus, as far as:

honóris causá, with due respect (for the sake of honor).
verbí gratiá, for example.
êius légis gratiá, on account of this law.
equus ínstar montis (Aen. ii. 15), a horse huge as a mountain (the image of a mountain).
laterum tenus (id. x. 210), as far as the sides.

NOTE 1: Of these the genitive with causá is a development from the possessive genitive and resembles that in nómen ínsániae (§ 343. d.). The others are of various origin.

NOTE 2: In prose of the Republican Period prídié and postrídié are thus used only in the expressions prídié (postrídié) êius diéí, the day before (after) that (cf. ``the eve, the morrow of that day''). Tacitus uses the construction with other words: as, - postrídié ínsidiárum, the day after the plot. For the accusative, see § 432. a. Tenus takes also the ablative (§ 26).