Today’s page has two sentences. The bare bones of the first sentence are Jessica epistolam ponit Jessica places a letter. The Adverb itaque and so joins this sentence with what has come before. epistolam a letter is described by the Perfect Active Participle scriptam which means having been written. scriptam is a form of the Verb scribo scribere to write. scriptam is expanded upon with the Adverb celeriter quickly. Further detail is added to ponit places by the Prepositional Phrase in limine on the threshold, telling us where Jessica is placing the letter. limine is further defined by the Genitive Marcelli of Marcellus.
Jessica therefore places a quickly written letter on the threshold of Marcellus.
The bare bones of the second sentence are utinam Marcellus epistolam inveniat which is not able to be translated word for word into English. The Adverb utinam is not usually translated at all, as it simply signposts that what follows is expressing a wish. The Verb following utinam will be in the Subjunctive Mood, as inveniat might he find is here. Basically, the narrator is expressing a wish that Marcellus find the letter. The second half of this sentence antequam Marcellus ipse inveniatur means before Marcellus himself is found, inveniatur being a Passive Verb. antequam before is a Conjunction. ipse, which describes Marcellus, means himself.
Hopefully Marcellus finds the letter before Marcellus himself is found.