On the 1851 census... John Cory Withers born 1838, Parents John and Mary Withers, Bristol. There is also a nephew Gostwacke Marcy age 17 born 1834
I agree with Tati - I read it as Gostwycke Marcy, born Bristol
and, although I have not found this one on Free BMD there is one other Gostwycke (Cheeswright, born Rotherham in 1887) so evidently a name even if not well used!
In the 1841 census
County of Bristol, St Nicholas (part of)
Address - Queen Square
HO107/373/9/32/12
Edward Masey, 47, Cooper
Elizabeth do, 45, no
Elizabeth do, 20
Maria do, 16
Mary do, 15
Frances do, 13
Gostwycke do, 7
Edward do, 21
(all born in county with the exception of Elizabeth aged 45)
Regards
Nell