Savage says on page 110 that this Arthur of Hartford is probably not the son of the immigrant ancestor, Arther Smithe, but the baptism record and father's will indicate that he probably was the son of Arther Smith the immigrant.
His father's will said he was to eventually have "the real estate in Hartford".
Arther, son of Arther, baptized 20 APR 1651 1st Church, Hartford, Hartford, CT
Connecticut Vital Records to 1870 (The Barbour Collection)] Hartford, CT pag 293. Citing 
Torrey's New England Marriages to 1700 (subscription)] Vol 2, page 1387.Citing 
Early CT Probate Records - Vol II] by Charles William Manwaring; Page: Vol II p 296 Citing 
James & Lucy Goodwin families] by Frank Farnsworth Starr, and James Junius Goodwin, 1915 Citing