110 cut from the sidewall 101 of the wellbore 100 as the reamer 10 advances therealong fig1 force applied to the apparatus 1 through the drill string and rotation of the rotatable abrasive reaming tube 11 cuts the crescent shaped core 110 which is received into the core receiving passage 61 as a continuous core 110 the length of the core 110 is limited only by the length of the core receiving passage 61 and therefore the core 110 can be of significant length during the coring process fluid which has been diverted from the housing 50 into the fluid bypass conduit 60 exits through fluid ports 62 at the bottom end 15 of the reamer 10 into the wellbore 100 for cleaning debris resulting from the coring and for cooling the coring head 63 preferably a diamond core head 63 is fitted to a bottom face 17 of the reaming tube 11 for cutting the core 110 the coring proceeds at a bottom 103 of the window 102 by pushing the apparatus 1 rotating the abrasive reaming tube 11 and circulating fluid therethrough with reference to fig1 a and 14 b core retaining means 70 are positioned adjacent a bottom end 64 of the core receiving passage 61 for retaining the core 110 therein in a preferred embodiment the core retaining means 70 is a finger 71 biased outwardly by a spring 72 into the core receiving passage 61 the core 110.