Your drums should have whats known as the "Sound King" lugs. The term Beavertail can be confusing as three different manufacturers use lugs that have been nicknamed beavertail and none of them look anything alike. Slingerland used a "beavertail" lug up to the mid-50's on the radio king series drums, after that they changed to the sound king style like you have. Rogers used a lug up until the early 60's nicknamed the "bread & butter" lug, mainly because it resembles a loaf of bread and there were several styles of these, but the originals were made of drawn brass and will (and do/did) crack under high tensions because of this. There is a guy in Texas who is replicating them out of steel now so they are stronger than the originals but he has the market cornered on them right now, so they are expensive. After the early 60's Rogers started using a cast lug nicknamed the "beavertail" lug, and it rather does resemble a beaver's tail, so the nickname fits this one more accurately. Leedy is the third manufacturer to have a lug nicknamed beavertail, and it resembles more of an art-deco design than a beavertail so I have no idea how they got stuck with that moniker.....
Hope this long-winded post clears things up a bit for you.