270 in cooperation with tabs 220 and 222 will hold the vertical center line plane of mudsill anchor 200 perpendicular to the plane of form board 320 and prevent lateral twisting or turning of anchor 200 during installation of the concrete slab dashed lines show the position of nailable tab 272 when imbedded in form board 320 to prevent uplift forces from lifting mudsill anchor 200 up from form board 320 still with reference to fig9 reinforcing rod tab 264 has been bent around reinforcing bar 340 as by a blow from a hammer or the like to attach it to leg 218 shown in dotted lines are attachment arms 216a and 216b which have been bent upwardly to engage the outside vertical side of mudsill 326 and bent again at bend line 300 to wrap around mudsill 326 and cover a portion of the top of mudsill 326 where attachment arms 216a and 216b are attached to mudsill 326 by nails 346 with reference to fig1 a and 10b there is illustrated a further embodiment of anchor 10 in the vicinity of the gripper member or pressure plate 70 in fig1 a in lieu of nailable tab 72 one or more gripper prongs 102 are provided which project inwardly toward inner surface or face 122 of form board 120 tip 104 of gripper prong 102 is adapted to point upwardly so that it will incise and frictionally engage inner face 122 of form board 120 shown in dashed or phantom lines and prevent any uplift forces on anchor leg 18 from causing anchor 10 to be lifted off of the top edge of form board 120.