You can use the name() or local-name() XPath function.
name()
local-name()
See the examples on zvon.
I know it's a bit outdated but you should do: xml.xpath('//meagerie/*[not(penguin)]/name()') as the expression. Note the slash, not the dot. This is how you call methods on the current node in XPath.
xml.xpath('//meagerie/*[not(penguin)]/name()')