Trouble with Whelks

[Jeff D]

These were seen snorkelling at Stony Beach in Woods Hole on Cape Cod.
I think the first one is a Common Whelk (Buccinum undulate), the next two perhaps a small Channeled Whelk (Busyrotypus canaliculatus) and the last one a Dog Whelk (Nucella lapels). None of these were larger than an inch and were located on a pebbly bottom in two feet of water. Can anyone confirm these ID's or suggest a different one?
Thanks again.