What is Rex jelly?

Rex Jelly was sold in the 1930s 40s 50s and 60s (that I know of). It was a unique mixture of fruit flavors that resembled raspberry but was not so dense. The filling that used to be in jelly donuts is as close as I have come, but for some reason, it has been changed. It was the favorite jelly in our family (my granddad used to say it was made from horses hoofs). Be that as it may, it was sure good on toast, biscuits and even with coconut cake. Wish I could find it again. The stuff sold online (Amish and all that...just seedless raspberry and not at all the same).