Wazir and Webb
They are very scrupulous in their dealings and emphasise on their publicity material that they do not under any circumstances deal in simian bipeds closely related to the human race. It might just be that the Librarian comes round every so often to assure himself this is indeed the case.
Indeed, they boast of only dealing in quadrupeds, but it is hard to reconcile this with their advertisement that states they also deal in birds. Unless, of course, with that usual Ankh-Morporkian exactitude, they consider that two wings are the other two peds that, in conjunction with feet/talons/webbed toes, make up a quadra.
Ankh-Morpork does not yet have a zoo. It is possible that Wazir and Webb deal with the Palace Menagerie, and with other private buyers - although Captain Carrot has said there is such a thing as a Dangerous Animals Act. As the city is a principal port, it is possible that live animals unloaded here from abroad are then shipped by road to institutions such as the Quirm Zoo.
No known connection to Mr. Wazir, a bookseller in Widdy Street.