Thirty stayers remain in contention for the Caulfield Cup following third declarations.

Turnbull Stakes winner Hartnell was on Tuesday paid up as an acceptor for the $3 million 2400m-handicap on October 15 with the Godolphin stable keeping its its options open by also declaring him for the Cox Plate at Moonee Valley on October 22.

Four of the 15 spring international horses that arrived in Melbourne on Saturday are among Caulfield Cup acceptors.

Scottish, a Godolphin-owned stayer trained by Charlie Appleby, Andreas Wohler's Articus and the Aidan O'Brien-trained Sir Issac Newton represent international trainers while Exosphere will run for Lee and Anthony Freedman.

The quartet is continuing preparations at Werribee racecourse while undergoing two weeks quarantine.

The field limit is 18 with four emergencies and there are currently 25 horses qualified to run.

Defending champion Prince Of Penzance is one of seven horses from the Darren Weir stable paid up as first acceptors for the Melbourne Cup on November 1.

Original topweights Order Of St George and 2014 Cup winner Protectionist were not paid up, meaning weights for this year's Cup will rise a minimum of a half-kilogram when final declarations are taken on October 29.

A total of 52 horses remain in contention for this year's race of which 36 are so far qualified.

Of the 52, 12 are international gallopers with four yet to qualify.

Winx headlines the list of 29 horses remaining in the Cox Plate with Sir Issac Newton and Vadamos the only two internationals.