in iis

[pmda]

Orberg in Exercitia Latina LLPSI Cap XXXVII scripsit:

Forum Romanum multis aedificiis publicis cingitur, in iis duabus basilicis, Aemilia et Iulia.

I don't understand the idiom 'in iis....' is it 'such as'....? Is he giving an example of buildings that surround the Forum...? What literally does 'in iis' mean in this sentence....?

[Carolus Raeticus]

Salve pmda!

Forum Romanum multis aedificiis publicis cingitur, in iis duabus basilicis, Aemilia et Iulia.

You are right, these are examples for buildings surrounding the forum (see here). It means amongst [the number of] these.
Cassell's dictionary gives the following meaning:

in. II. 4. amongst the number of; in quibus Catillina, Sall.

Orberg merely uses iis (used as a demonstrative to refer to something already mentioned) instead of quibus. Does anyone know, when exactly to use is, ea, id and when qui, quae, quod? The latter is common when refering to an antecedent in the previous sentence. Any other difference?

Vale,

Carolus Raeticus

[pmda]

Carole, Gratias tibi ago.

[adrianus]

Orberg merely uses iis (used as a demonstrative to refer to something already mentioned) instead of quibus. Does anyone know, when exactly to use is, ea, id and when qui, quae, quod? The latter is common when refering to an antecedent in the previous sentence. Any other difference?

Not to omit the obvious (unless I'm wrong), "in iis" means "in/among them/those/these" and "in quibus" means "in/among which". So in Latin as in English, I believe, if you say "The forum is surrounded by many public buildings, among them [by] two basilicas", the phrase "among them [by] two basicilas" is complementary (complementing "many public building", as "ut +" also can do in Latin); if you say "The forum is surrounded by many public building, among which [by] two basilicas", in the phrase "among which [by] two basicilas" you understand a verb to have been dropped from the phrase (either the previous one repeated or a new one "is/are"—here it can only be the "[forum] cingitur" when the nouns Aemilia and Julia are ablative). Something tells me "in quibus" doesn't work here in English or Latin, or doesn't work as well as "in iis". I don't think Orberg would have said "in quibus: for "in iis".

Ne omittatur res manifesta (nisi fallor), discrimen nota quod se et anglicè et latinè ostendit. Complementaria est "in iis" collocatio; "in quibus" autem collocatio clausulam introducit quae clausula verbum nisi subauditum requirit. Id malè sonitur cum "in quibus", ut suspicor, vel minùs benè sonitur quam per "in iis". Dubito an Orberg hîc scripsisset hoc: "in quibus".