referring now to fig1 there is illustrated hemostatic clip 10 constructed of two leg segments 11 and 12 connected at the proximal ends thereof by hinge section 13 . leg 11 terminates at the distal end thereof in hook member 14 having inner face 15 substantially parallel to inner face 16 of leg 11 and forming an acute angle with end face 17 . leg member 12 terminates at the distal end in end face 19 which forms an obtuse angle with inner face 18 of leg 12 . end face 19 is offset at 23 to form a notch approximately midway between surfaces 18 and 20 , and additionally is squared off at face 25 to form a substantially right angle with surface 20 . the length and width of faces 16 and 18 are substantially equal , and face 15 of hook 14 is spaced from face 16 of leg 11 by a distance corresponding to the thickness of leg 12 between the plane of face 18 and surface 20 . when legs 11 and 12 are pivoted about hinge 13 to bring faces 18 and 16 into opposition , hook 14 is deflected by surface 19 of leg 12 until the desired end of leg 12 snaps under hook 14 and is thereby locked in place . end face 17 of hook 14 and end face 19 of leg 12 are angled as illustrated to facilitate the passage of leg 12 past hook 14 during clip closure . when the clip is closed over a tubular vessel as illustrated in fig2 surfaces 16 and 18 engage and compress vessel 27 to close the lumen thereof . surfaces 16 and 18 may be smooth as illustrated in fig1 or may be provided with ridges or grooves to increase vessel holding power . leg 11 may also be undercut at the juncture of hook member 14 and surface 16 as illustrated at 26 in fig1 to increase the deflectability of hook member 14 and increase the space between the hook member 14 and leg 11 , thereby compensating for any inward deflection of hook 14 during closure which might reduce the clearance between surfaces 15 and 16 and otherwise interfere with the latching of the clip . referring again to fig1 leg 12 of clip 10 includes an outside cylindrical boss 21 extending across the width of the leg near the distal end thereof . boss 21 is spaced from surface 25 a distance sufficient to permit full engagement of hook member 14 by leg 12 when the clip is in a closed and latched position . cylindrical bosses 21 and 22 are equidistant from hinge means 13 so that when the clip is closed , bosses 21 and 22 define a line perpendicular to the major axis along the length of the clip as best illustrated in fig5 . the distal end of leg 12 forward of lug 21 is of reduced thickness relative to the thickness immediately to the rear of lug 21 , thereby forming step 24 between lug 21 and surface 20 . the significance of this clip configuration will be appreciated in connection with the instrument used to apply and close the clip as illustrated in fig3 through 5 . fig3 illustrates a forceps - type ligating clip applier 30 comprising two handle members 31 and 32 crossing at hinge point 33 and maintained in a normally open position by spring 38 . handle 31 extends beyond hinge 33 forming jaw member 34 while the extension of handle 32 forms jaw member 35 . fig4 illustrates the detail of the construction of jaws 34 and 35 and the interaction of the jaws with the clip of fig1 . jaws 34 and 35 are of identical design and are provided respectively with channels 36 and 37 extending rearwardly from the tips of the jaws . each channel is provided with a cylindrical recess 38 and 39 respectively across the width of the channel and near the distal end theref . recesses 38 and 39 are in alignment when the jaws of the applier are closed and are sized to receive the cylindrical lugs 21 and 22 of the clip . channels 36 and 37 forward of recesses 38 and 39 are deeper than to the rear of the recesses as illustrated in fig4 . when the open clip is held in the applier , the cylindrical lugs on the clip extend into the cylindrical recesses in each jaw . due to the angle of the clip in the applier , the distal ends of legs 11 and 12 extend into the deeper forward channel section of each jaw . the reduced thickness of leg 12 at the distal tip prevents interference between the tip and the channel of the applier when the clip is held in the open position as illustrated in fig4 . clip 10 is initially loaded in applier 30 in the open position as illustrated in fig4 . after moving the jaws of the applier and the clip into position over the vessel to be ligated , the jaws of the applier are closed and the clip is locked in position over the vessel as illustrated in fig5 . as the clip is closed , the cylindrical lugs of legs 11 and 12 rotate in the cylindrical recesses of jaws 37 and 36 until the outer surface of leg 12 rests on the base of channel 36 as illustrated in fig5 . at this point , the distal end of leg 12 has rotated away from the base of the channel and sufficient space exists for hook 14 to bypass leg 12 and latch over the outer surface thereof . after the clip has been securely latched over the vessel to be ligated , the jaws of the applier are opened to release the clip and vessel and a new clip is loaded in the applier . since the jaws of the applier are identical , it is not necessary to orient the applier to the clip when loading the applier . many variations in the clip design other than the embodiments disclosed herein will be apparent to those skilled in the art and are contemplated within the scope of the present invention . for example , the undercut at the juncture of hook 14 and surface 16 of leg 11 may be omitted , and the inner surface of leg 12 may be beveled at the distal end as indicated by broken line a in fig1 to compensate for downward deflection of hook 14 during closure which might reduce the clearance under face 15 and interfere with the latching of leg 12 . offset 23 in end face 19 of leg 12 provides an intermediate latching position and effectively increases the length of face 18 at the distal end of leg 12 , but may be omitted if desired . these and other modifications in the configuration of the clip may be employed without departing from the spirit and scope of the present invention . the clips of the present invention may be constructed in various sizes according to their intended function . hemostatic clips are typically less than 6 mm in length , about 1 . 5 mm in width , and have a vessel clamping surface about 3 mm in length . the dimensions of the clip may be reduced by about 50 percent for certain applications in microsurgery . larger clips for special hemostatic applications and other functions such as closure of oviducts or vas deferens may have dimensions of about double those of a typical hemostatic clip . the various sizes of clips are preferably matched with individual appliers having jaws tailored to the size of the clip for best performance . the clips of the present invention are most conveniently molded of biologically acceptable plastic materials which may be absorbable or nonabsorbable . preferred absorbable polymers include homopolymers and copolymers of glycolide and lactide , and poly -( p - dioxanone ). preferred nonabsorbable polymers include nylon and polypropylene . all these materials have been demonstrated to be biologically acceptable when used as sutures or other implantable medical devices . the clips may also be cast or machined from solid polymeric materials or from metals such as aluminum , magnesium , stainless steel , tantalum , various alloys of these , some of which may also be absorbable in biological tissue .