Spider with improbable IP address

["Ed Wittmann" <wittmann () sae org>]

A server I help maintain is currently being spidered, which is not so
unusual - however, I note that the address the spider is coming from
seems weird:

xxx.xxx.xxx.0


Now, I was under the assumption that you can't send and receive on this
address - but the requests come in here, and they're clearly going back
out here. The weblogs show this address.

Could someone cure my ignorance? Is this spoofing? It doesn't seem like
source spoofing since the reply is clearly going back to the same IP
address.