portion 43 of the peripheral wall 28 on the other long wall portion 44 of the peripheral wall 28 the insulating ring 40 does not have the integral extension portion 42 but the lower face 44 of the portion 45 of the ring 40 is in the same plane as the face 46 of the portion 41 of the peripheral wall 28 of the spinnerette as is more easily seen in fig2 the insulating ring 40 which is secured to the underside of the bottom housing 20 by screws not shown has the integral extension portions 50 51 extending over the lower faces of the portions 52 53 of the shorter lengths of the peripheral wall 28 of the spinnerette referring to fig3 this shows in perspective the spinnerette incorporated into the jet assembly the spinnerette generally 60 has an outer flange 29 integral with the wall 28 the rectangular nature of the spinnerette can clearly be seen from the perspective view in fig3 the minor axis of the spinnerette is shown in the sectional view of fig1 and the major axis is shown in sectional view in fig2 welded into the bottom of the spinnerette are six aperture plates 61 which three of the plates 30 31 32 seen in sectional view figure of fig1 these plates contain the actual holes through which the cellulose solution is extruded the spinnerette has an underside in a single plane and is capable of withstanding the high extrusion pressures experiences in spinning a hot cellulose solution in amine oxide fig4 is an underneath view of the spinnerette showing the location of the insulating.